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STUDIES ON X-RAY TREATMENT OF PHLOX

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The Pennsylvania State College
The Graduate
School
Department of Botany
Studies on X-ray Treatment of Phlox
by
John Stuver Bangson
A
Dissertation
submitted in partial fulfillment of the
requirements for the degree of
Doctor of Philosophy at
The Pennsylvania State College
.
August, 1940
Approved:
Professor of Botany
STUDIES ON X - R A Y TREATMENT OF PHLOX.
Contents.
I. Introduction
1
II. Materials and Method of Procedure
1
1. The Material
1
2. The Experiments
2
3. The X-ray Machine
•
3
4-. Unit of Measurement for Dosages
3
5. Experiment
I - Material, Technique
4
6. Experiment
II - Material, Technique
6
7. Experiment
III - Material,
7
8. Experiment
IV - Material, Technique
8
9. Experiment
V - Materials, Technique
10
Technique
III. R e s u l t s .
A. Physiological Results
a. Buds - reaction,
seed-setting
12
b. Seeds
1. S pe e d of germination
15
2. Percentages of germination
15
c. Pollen - reaction,
seed-setting
20
d. Seedlings - abnormal appearance
23
e. Lethal effects
24
B. Genetical Results
1. Foliage Color Studies
a. Yellow - origin, heredity, discussion
27
b. Mottled - origin,
29
heredity,
discussion
2. Flower Pigmentation
a. White - origin, discussion
33
b. Violet Flash - origin, heredity, d i s ­
cussion
35
c. Spinel Pink - origin, heredity, d i s ­
cussion
37
3. Stature
a. Giant - origin, discussion
39
b. Dwarf - origin, heredity, discussion
42
4.
Aborted Flowers - origin,
5.
Lethals - origin, discussion
IV. Summary and Conclusions
V. Literature
discussion
45
46
47
50
STUDIES ON X-RAY TREATMENT OP PHLOX.
This investigation was undertaken during the summer of 1931.
The purpose was twofold.
It was considered desirable to as­
certain if X-radiation might prove as effective in changing
the constitution of genes and chromosomes of Phlox Drummondii as it was shown to be when used with Nicotians spp.,
Pordeum s a ti vu m, Gossypturn hirsutum, Zea ma;/s, and other
plant material,
and Drosophila melanogaster among animals.
There was also a desire for a supply
of variations which
would be available for the prosecution of further studies
involving Phlox D r u m m o n d i l .
The Material - The material for the investigation consist­
ed of two families of Phlox Drummondil which had been self­
pollinated for several previous generations.
Each was uni­
form in X'Ggard to stature, and flower and foliage
colors,
and on the basis of progeny tests of untreated lines, both
must have been homozygous when the experiments were initiat­
ed..
One family (Fig.lb) had light bluish-violet**'" petals
with a star-eye.
The eye consisted of a flash in the center
of the petal near the throat, and two bars, one on each side
of the flash,
and slightly nearer to the base of the throat.
The pigment of the star-eye was
more intense than the other
parts of the petal.
*"'" kidgway's COLOR STANDARDS AP'D NOMENCLATURE was used in
determining all colors mentioned in this paper.
The foliage of this famil3r was slightly lighter than spin­
ach green.
In the greenhouse the plants displayed a tend­
ency to produce a main st e m with slight branching, while
in the field several main branches developed, each of which
had many secondary branches.
The greenhouse cultures of
this family were about 33 cm. in height.
The flower color of the other family (Pig.la) was tyrian
pinlc, and there was a star-eye that was slightly darker
than spinel red.
The foliage v/as grass green;
house height was 25-30 cm.
the green­
vhe habit of growth was the
same as the other family.
The Experiments - Five experiments were undertaken.
In
the first experiment the treated material was immature buds;
dry seeds were used in the second experiment, while soaked
seeds were treated in experiment three.
Ivlature and imma­
ture pollen was irradiated in experiment four,
last experiment pollen and buds were exposed.
and for the
The X-ray Machine - The machine employed for irradiating
this material was an upright type (Fig.2) with the tube
housing surmounting a shelf which surrounded it entirely,
hear the base of the housing there were fifteen windows,
three-fourths of an inch square,
closing covers.
and with automatically
It was through these windows that the
material extended while being treated.
Except for the
last experiment, the X-ray tube had a molybdenum target;
in that experiment a tube with a copper target was em­
ployed.
This machine was the property of the X-ray Labor
tory, The Pennsylvania State College.
Unit of measurement - The mllliainpere-minute*v“
' was the
unit of measurement that was used to calculate dosages.
It is computed, as follo ws :
Hilliampere-minute (MAM)
0.251
t
I
E
d
0.251 x t x I x E 2
-------------------d2
- correction.
- time of raying in minutes.
- current through the tube inrailliamperes.
- voltage across the tube inkilivolts.
- distance from the target to the specimen in cm.
* Permission for its use was generously granted by Doctor
W.P.Davey,
Research Professor of Physics and Chemistry.
Suggested by Doctor W.P.Davey.
Experiment I - As was previously stated,
the treated mater­
ial in this experiment consisted of immature "buds.
greenhouse phloxes grow strong terminal buds.
generally very little branching,
quent.
In the
There is
and tillers are infre­
In preparing the first portion of the material that
was treated in this experiment,
the terminal bud was pinch­
ed out when the seedlings were about four inches tall. This
gave two equally strong lateral branches.
diating was done,
the buds of one branch were treated, the
buds of the other branch were controls.
of treating,
When the irra­
During the process
the control buds were well protected from X-
rays, not only by the walls of the tube housing, but also
by very thick portions of lead which were placed between
the outside walls of the machine and the control buds.
The clusters of buds to be treated were very carefully ad ­
justed so that they would be at the proper distance (10 cm)
from the target of the X-ray tube.
very difficult to attain.
Sometimes this was
It is very obvious that the dis­
tance between the treated material and the target,
ences greatly the dosage of the treatment.
influ­
Cotton and
small corks were also used to protect the delicate stems of
the plants from injury through contact with the window
covers and the walls of the machine.
After treatment,
the plants were placed in the greenhouse.
Before any of the buds opened,
glassine bags of an appro­
priate size were fastened over the clusters.
Later, when
the buds opened, the flowers were self-pollinated.
The phlox flowers which were used in all of these experi­
ments were salver-shape cl..
There are five stamens which
are adnate on t h e tube of the
is accomplished easily.
flower.
Self-pollination
The tube is severed longitudi­
nally on opposite sides down to the level of the stigma;
the pollen is then pushed down upon it v/ith a sterile
needle.
All needles were sterilized in the flame of an
alcohol lamp.
Experiment II - Dry Seeds.
This experiment dealt with dry seeds.
The seeds of each
plant were divided into two groups of about equal numbers.
Each portion was confined in small squares of double
two
cheesecloth.
The seeds of one of the/packages from the
same plant were treated;
the other seeds were used as con­
trols.
All control seeds were left in the greenhouse.
The seeds
to be treated were placed inside the windows of the X-ray
machine at the proper distance from the target,
diated.
and irra­
A check was made to ascertain if the cheesecloth
absorbed any energy;
the results were negative.
After the containers were removed from the X-ray machine,
they were placed outside the treatment room with those yet
to be treated, where they received no additional X-rays.
After the treatments were completed,
to the greenhouse,
and treated and control seeds were
sown in soil from the same mixing.
were transplanted,
the same mixing.
the seeds were taken
they, also,
When the seedlings
were put into soil from
Experiment III - Soaked Seeds.
The seeds which were selected for this experiment were soak­
ed in tap water for forty-two hours.
The time of soaking
was arbitrarily determined as the time after which soaking
was started when the cells of the embryo were is a very
active condition.
It was felt that the genes and chromo­
somes of active cells would be more susceptible to altera­
tions through the action of X-rays than dry seeds.
The seeds of each plant were soaked separately in prepara­
tion dishes.
At the end of the soaking period, the seeds
were divided into two almost equal portions,
one portion of
the seeds of each plant was designated for treatment,
other portion v;as used as controls.
the
As a precaution to
prevent evaporation during the process of irradiation, the
seeds were kept moist in wet paper,
and the paper with its
seeds was contained in the same type of cheesecloth sacks
as were used for the treated seeds in Experiment II.
Tests
indicated that the paper did not absorb any appreciable
quantity of energy.
Aside from soaking,
the seeds in this experiment were hand­
led in the same manner as the dry seeds in the previous ex­
periment.
Treated and untreated seeds were germinated
separately under the same conditions of moisture and tem­
perature,
and the seedlings and mature plants were grown in
close proximity in the greenhouse,
or in the field.
Experiment IV - Pollen
In this experiment pollen in various degrees of maturity
was used as experimental material.
It will be recalled
that in Phlox Drurnmondii the stamens are attached to the
corolla tube, so that when the corolla is removed,
stamens are removed with it.
In a mature,
the
or almost mature
flower, the removal of the corolla does not interfere with
the pistil.
Just previous to the opening of the flower, the anthers
were examined to determine whether or not they had dis­
charged their pollen.
If the anthers had not opened,
they were selected for treatment.
The matter of knowing
the approximate time when the anthers will open is not
difficult,
for there is a definite correlation between
the opening of the flower and the discharge of the pollen
by the anthers.
The pollen of about one-half of the anthers of a plant
was used for self-pollinating their own flowers, and
these flowers served as controls.
The corollas of the anthers which wei’e selected for irra­
diation were split on opposite sides,
and then they were
placed in double cheesecloth sacks for treatment.
The
same technique was followed as was used in the other ex ­
periments •
Seventy-three plants were used in this experiment.
dosages varied from 64 1/IA.M to 1051 MAM.
The
The material
from any one plant was given the same dosage.
Treated
pollen was placed u pon the flowers of the plant from
which it was taken, hut no attempt was made to pollinate
flowers with their own pollen.
Experiment V - Pollen and Buds.
The material dealt with in this experiment consisted of
buds of varying degrees of maturity,
instances the pollen was mature,
and pollen.
In most
or nearly mature.
The same technique was employed in this experiment as was
used in the previous experiments where the same materials
were involved.
The target of the tube was copper.
Plants arising from dry and soaked treated seeds,
seeds resulting from treated buds and flowers,
from
from seeds
resulting from treated pollen and untreated ovules, and
from all of the control material, were self-pollinated,
when viable,
for from four to seven generations.
The plants were grown in the greenhouse and in the gar­
dens of the Department of Botany, The Pennsylvania State
College,
and in the greenhouse and garden of the Depart­
ment of Biology of Berea College.
When feasible,
treated
and control plants were grown in adjacent rows in the
field, and in the garden they were in close proximity.
Each plant was critically examined for any divergence
from the original types,
and records were made. Differ­
ences which were observed in all of the progenies from
treated and from untreated germ cells, were painstakingly
examined, and their flowers were self-pollinated to as­
certain whether or not the variations were heritable.
PHYSIOLOGICAL RESULTS.
Buds - In many instances, particularly after the heavier
dosages were administered, large numbers of buds were not
able to survive the treatment.
off.
Many were able to survive,
In a few days they fell
and they developed seeds,
but not always in abundance.
Following (Tables I & II) are summaries of the seedsetting percentages of treated and untreated buds.
These computations were based upon three seeds to the cap­
sule, as is normal for Phlox Drummondi i.
The number of
flowers was multiplied by three to get the number of poten­
tial seeds.
The number of seeds which were produced was
divided by the number of potential 3eeds to determine the
seed percentages.
Table I - Summary of Seed-Setting Percentages of Treated
and Untreated Buds, Target of Tube Molybdenum
UNTREATED
Dosage No.FIs. No.Sds.
MAM
PercM
o.Fls.
No.Sds. Perc1
26
32
75
78
20
55
91
53
28
71
85
19
52
91
62
352
684
85
246
685
93
125
948
1730
61
787
2145
91
187
526
651
41
468
1288
91
252
1108
1097
53
1155
3014
87
312
647
383
20
600
1638
91
378
1052
347
11
832
2171
87
437
250
120
16
235
627
89
509
920
303
11
701
1893
90
567
337
1112
11
292
697
91
630
1105
245
7
867
2367
91
700
131
43
11
158
431
91
765
514
93
6
396
1081
91
908
234
4-2
6
175
436
33
1025
380
57
5
293
836
96
1071
96
11
4
118
382
91
14
Table II - A Summary of Seed-Setting Percentages of Treated
and Untreated Suds, Target of Tube Copper.
TREATED
Dosage No.FIs.
MAM
UNTREATED
No.Sds.
Perc't
No.FIs.
No.Sds.
P e r c ’t
61
159
420
88
146
423
97
123
162
334-
69
128
366
95
185
185
381
69
135
377
93
246
222
349
52
138
444
94
311
178
200
38
155
396
85
372
172
125
24
131
359
91
I
Germination - a. Speed of germination - An immediate effect
of X-rays upon dry and soaked seeds was a delay in germina­
tion.
Generally from ten days to two weeks are required for
the germination of phlox seeds, and the untreated seeds of
these experiments displayed that habit.
But the treated
seeds were delayed a week or more in coming through the soil.
There seemed to be a correlation between the intensity of
the treatment and the extent of the delay in germination
(Pigs. 3 & 4).
Those seeds which were given relatively
liglit dosages displayed very little delay.
Goodspeed (1929)
reported delayed germination for seeds of
Nicotiana tabacum which had been X-rayed.
Our dosages were
in excess to those administered by Goodspeed.
b.
Percentages of germination - The germina­
tion percentages are interesting.
tables III o: IV.
They are illustrated in
Irradiation did not interfere greatly
with the percentages of germination of dry seeds, but the
higher dosages were disastrous to a large portion of the
treated
soaked seeds.
Eighty-seven percent of all/dry seeds ger­
minated, while 93/;’ of their controls germinated.
But only
33,o of all treated soaked seeds germinated, as compared
with 92>o of their controls.
It is obvious that X-rays are
more deleterious to active seeds than to inactive seeds.
The following tables
(III & IV) show the germination per­
centages of dry and soaked treated seeds,
and their controls.
16
Table III- A Summary of Germination Percentages of Treated
and Untreated Dry Seefe.
TREATED
)osage
MAM
Uj,!TREA TED
No.Sds. No.Sds.
Germ
P e r c ’t
Germ
No.Sds.
No.Sds.
Germ.
Perc’
Genr
626
78
66
85
66
54
82
745
80
72
90
68
52
77
868
80
56
70
44
4-4
100
969
214
196
91
148
141
95
1070
110
150
88
114
112
98
1175
140
112
80
94
36
92
1276
63
57
90
52
36
70
1577
40
24
60
28
20
71
1476
72
48
67
38
38
100
1574
56
52
93
42
42
100
1684
68
56
83
48
48
100
1807
61
60
98
60
60
100
1842
96
90
94
83
77
93
1908
50
50
100
40
40
100
1988
96
90
94
82
78
93
2008
51
42
80
41
39
95
2108
66
56
85
46
46
100
2127
100
94
94
68
60
88
2239
98
92
94
68
60
88
2209
51
45
88
50
48
96
Table III - concluded.
TREATED
UNTREATED
Dosage
MAM
No.Sds.
No.Sds.
Germ.
2309
55
52
94
44
42
95
2409
55
52
94
60
60
100
2 51 0
57
51
89
45
45
100
2 71 1
80
56
70
66
58
88
Perc't.
Germ.
No.Sds. No.Sds.
Germ.
P e r c ’t
Germ
1-8
Table IV - A Summary of Germination Percentages of Soaked
Seeds, Treated and Untreated.
TREATED
No.Sds.
Germ.
UNTREATED
P e r c' t.
Germ
osage
MAM
No.Sds.
Tr'd.
195
21
16
76
18
16
89
261
31
29
94
27
25
93
293
25
20
80
21
18
86
380
42
36
86
35
34
97
389
26
22
85
18
16
89
490
32
26
81
27
24
89
524
35
30
86
31
29
94
588
32
22
69
27
22
81
652
33
30
91
27
25
93
686
33
20
61
25
25
100
762
29
22
76
25
22
88
785
26
15
58
23
22
96
819
25
15
60
22
20
91
981
33
22
67
32
26
88
1050
40
21
53
20
19
95
1080
22
11
50
18
15
03
1175
192
97
51
162
152
92
No.Sds. No.Germ. P e r c ’'
Germ
m
Table IV - concluded
TREATED
Dosage
MAM
UNTREATED
No.Sds. No.Sds. P e r c 1'
T r 1d.
Germ.
Germ
rlo.Sds. No.Germ. P e r c ’t.
Germ.
1275
130
60
46
113
109
96
1306
28
12
43
25
23
92
1380
89
33
37
82
73
89
1441
20
7
33
28
25
89
1475
150
27
18
131
123
94
1575
114
19
17
87
84
97
1585
25
1
4
21
20
95
1703
23
8
35
20
19
95
Assembling the data of the experiment,
it will be ob­
served that the soaked seeds which were treated have a
germination percentage of 49$, while 92$ of the control
seeds germinated.
Whe n these data are compared with
those gotten from treated and untreated dry seeds,
we
have,
Treated
Untreated
Dry Seeds
87$
9 0/6
Soaked
49$
92/o
Seeds
Collins and maxwell
X-rays*
(1936) treated dry maize seeds v/ith
The seeds were always irradiated with the embryo
side facing the source of the X-rays.
They found that
very high dosages did not affect adversely the germination
of seeds.
Goodspeed (1929a,
1929b) reported that soaked
seeds of Hicotlana tabacum were more sensitive to X-rays
than were dry seeds.
Iienshaw and Francis
(1933) found
the same to be true for seeds of Triticum vulgare.
This
was also the observation of Lambert (1933), and Stadler
(1928) from work v/ith barley.
Pollen - X-rays had a deleterious effect upon pollen,
the following tables (V and VI) indicate.
as
21
Table V - Summary of Seed Production Percentages from
Treated and Untreated Pollen,
j;
I
V
Target of Tube Molybdenum.
TREATED
Dosage
itlAi/i
i
UNTREATED
No.FIs. LTo.Sds.
Perc't.
No.Pis. No.Sds.
t
Perc't.
64
104
109
35
81
217
89
127
107
123
43
83
211
80
195
129
26 6
58
114
29 8
87
260
165
308
62
133
355
89
325
130
217
56
10 5
278
88
388
117
192
55
107
256
80
450
130
213
55
110
283
86
528
18 8
284
50
1 59
408
86
600
139
186
4.5
135
347
86
668
13 6
174
43
107
’ 307
96
732
136
157
38
112
29 1
86
795
122
138
38
10 1
22 1
73
859
91
102
37
73
198
90
923
67
62
31
50
1 31
87
987
14
12
29
9
21
73
1051
23
21
30
20
53
88
.
m
22
Table VI - A Summary of Seed Production Percentages of
Treated and Untreated Pollen; Copper
Target.
TREATED
UNTREATED
Dosage No.FIs. N o . S d s .
P e r c ’t .
No.FIs.
No.Sds.
Perc
iiiA ivi
63
137
333
81
104
284
91
125
121
273
75
83
225
90
191
121
255
76
93
262
94
252
152
341
75
124
34-2
92
316
135
233
58
128
368
96
378
165
192
39
125
381
94
441
162
149
31
136
369
90
505
186
46
8
65
180
92
569
79
10
4
74
213
96
The Seedlings - It will he observed from figure 3 that
seedlings from irradiated seeds, which were able to sur­
vive the treatment, appeared stunted and weak.
This ef­
fect persisted for several weeks, but gradually the plants
assumed a normal appearance.
At maturity there was no
evidence of this earlier retardation,
and the seeds which
these plants produced were as viable as the seeds of the
control plants.
Stunted progeny were observed from dry
and soaked seeds alike.
24
Another effect of X-ray treatment of dry and soaked seeds
was the appearance of abnormalities that were observed in
some of the first few leaves.
Sometimes they were twist­
ed; some of the leaves were bifurcated;
they were very small.
in other instances
Some of these forms are illustrat­
ed in figures 5, 6 and 7.
These abnormal leaves never as­
sumed a normal appearance, and they never reached the oroportions of normal leaves.
Further leaves which these
plants produced were normal.
Goodspeed (1029) observed distorted leaves in his progenies
from X-rayed seed3 of ilicotiana tabacum, and Horlacher and
Killough (1931) made the same observation in the progenies
of Gossypium hirsutum from treated dry seeds.
Lethal Effects - In the second and third generations after
treatment numerous instances were encountered where appar­
ently normal seeds failed to germinate.
A peculiar attri­
bute of some of these cultures was that frequently the
entire culture was not viable, but among the sibs from
treated ancestry, the germination was high*
Details of
several of these lethals follow:
a.
Twenty-three buds of culture 396 were given a dosage
of 625 i.iAi'.i; 11 seeds developed,
able to germinate,
hone of these seeds was
although they appeared normal, but 53
seeds from 13 control buds of the same plant germinated
end developed into normal plants.
b. Twelve buds of culture 126 were treated with a
dosage of 437 MAM.
Twenty-two seeds resulted.
these was able to germinate.
None of
Ten untreated buds of the
same plant developed 26 seeds; all of these were viable.
c. Albino - This form arose from bud raying.
of 430 MAM was administered to 12 buds;
A dosage
one seed resulted.
The plant from this seed developed chlorophyll, and it
presented the appearance of a normal plant.
pollination,
Prom self-
33 plants resxilted in the next generation.
All of them were albino,
ho albino plants were observed
among the 271 controls.
As far as it is known,
albino was never encountered pre­
viously in Phlox D r u m a o n d l i , although this character ap­
pears abundantly in nature.
It is found in Antirrhinum
ma.jus, Delphinium spp., horde urn sativum, bicotiana spp.,
Gossypium liirsutum, Trltioum spp., and Zea m a y s , to m en­
tion a limited number (katsuura, 1933).
Pew references in the literature have been observed which
indicate that albinism has been induced in plants through
X-rays, although Stadler (1931) reports that in maize
"white seedling is the most common mutant type."
GENETXCAL RESULTS
Variations which were ohserved over a period of from 4-7
generations, and lethal and other forms which were lost,
but which were genetical, arrange themselves in the foll­
owing grouping.
1. Foliage Color Studies.
a. Yellow (cosse green)
- from grass green.
b. Mottled - from grass green.
2. Flower Pigmentation.
a. White - fr om the violet type.
b. Flash - from the violet type.
c. Spinel pink - from the violet type.
3. Stature.
a. Giant - from the violet type.
b. Dwarf - two appearances, one from the violet
type, one from the pink type of flower.
4. Aborted flowers.
5. Lethal - two appearances.
As will be demonstrated subsequently, all of these varia­
tions are gene differences,
except, perhaps, the giant and
the white-flowered type.
We shall now consider in more detail the characteristics,
origin and inheritance of these diverse forms.
1. Foliage Color Studies.
a.
Yellow - This form (Fig.8) arose in the second
generation after treating 56 dry seeds of culture Til
with a dosage of 1574 MAY.
lings.
It was observed in 3 seed­
The foliage of the ancestry of these seeds was
slightly darker than grass green.
The mutation was uni­
formly colored from the first observation,
was retained throughout its existence.
control seeds.
and this color
There were 52
In this second generation there were 975
individuals from treated parentage.
consisted of 854 plants,
The control group
and no yellow plants appeared
among them.
This mutation,
as far as it is known, never appeared pr e­
viously in Phlox D r u m m o n d ! i > although what appears to be
analogous is known in many other plant species, as Antir­
rhinum m a j u s , Crepis canillaris, ilicotlana tabacum, Pisum
spp., Triticum spp., Zea m a y 3 , and others
(Yatsuura,
1933
DeKann, 1933).
This variation has bred true through self-pollination for
six generations, and when it was combined reciprocally
with unrelated green plants,
segregation occurred in the
B’g in true simple mendelian fashion.
led in the following table
(VII).
The data are assernb
Table VII - Summary of Second Generation Progenies of Re­
ciprocal Grosses Between Yellow and Green.
142.3
(yellow) x 321.1 (green)
33
green
9 yellow
115.8
(yellow) x 321.2 (green)
41
green
11 yellow
172.3
(green) x 118.4 (yellow)
27
green
7 yellow
132.3
(green) x 142.9 (yellow)
50
green
12 yellow
Total
151 green
39 yellow
Calculated
142.5
green
47.5 yellow
f8.5 green
-8.5 yellow
Deviation
The deviation divided by the probable error of the ratio*'
and indicates
(D/P.B.) is 2.1,/a good fit of theory to fact.
Stadler (1930, 1931b) reports that various yellows were
induced by X-rays in maize, and also in barley.
them behave as simple recessives.
mutations are recognizable
All of
In barley 90/ of all
in the seedling stage, and
nearly all of them are chlorophyll deficiencies, of which
about 15/ are yellow.
in the same manner.
In maize yellow mutations behave
Horlacher and K i H o u g h (1931, 1932,
1933) induced virescent yellow in cotton through X-rays.
It proved to be monofactoral in its heredity.
An inter­
esting fact is that a reverse mutation was produced by
X-radiation
P.E.
-
through treating a ye H o y / virescent plant.
.6745 / P x Q, x n
-
.6745/.75 x .25 x n
29
The reverse mutation was "larger,
thriftier and more vigor­
ous than the virescent yellow plants from the same bolls."
Horlacher and Killough (1932) described a yellow mutation
which was devoid of chlorophyll,
and lethal.
It segregated
as a simple recessive.
MacArthur (1954) was able to induce
yellow-white variations
in the tomato by the use of X-rays.
He did not kn o w the heredity of this mutation, but he sug­
gested that it may be either a lethal,
or a dominant.
b. Mottled - A second foliage variation, mottled,
non-mottied
arose from the/grass green stock.
This mottling may be
described as irregularly angular areas of grass green and
yellow of almost equal dimensions.
In instances it seems
that the yellow areas are more closely associated with the
veins of the leaves.
It is shown in figure 0.
Mottled arose from dry seeds of culture Til which were given
a dosage of 1684 MAM.
It was first observed in one plant.
There were 48 treated and 46 untreated seeds.
In the second
generation after treatment there were 752 plants from treat­
ed ancestry,
and 651 plants in the control group.
in this generation that mottled appeared.
It was
mottled has bred
true for six generations through self-pollination.
Follow­
ing are the Fg progenies of reciprocal crosses between mot­
tled and unrelated grass green plants.
Table VIII - Summary of Second Generation Progenies of
Reciprocal Crosses Between Mottled
and Green.
210.3 (mottled) x 318.2 (green)
18 green
4 mottled
210.6 (mottled) x 318.6 (green)
43 green
12 mottled
219.4 (mottled)
39 gr e en
12 mottled
(mottled)
43 green
11 mottled
174.8 (green) X 326.8 (mottled)
35 green
9 mottled
x 318.5 (green)
173.9 (green) X 326.7
318.1 (green) X 210.2 (mottled)
21
green
4 mottled
Totals
199 green
52 mottled
Calculated
188. 25 green
62. 75 mottled
Deviation
*10. 75 green -10. 75 mottled
The difference divided by the probable error of the ratio
is 2.3 which indicates that fact and theory fit.
Yellow and mottled were crossed reciprocally.
generation was green,
are not alleles.
crosses are shown.
The first
indicating that jellow and mottled
In table IX the ? 2 progenies of these
Table XX - Summary of Second Generation Progenies of Recip­
rocal Crosses Between Mottled and Yellow.
Yellow x Mottled
F2
115.2 x 210.1
71 green
25 mottled
31 yellow
116.5 x 210.2
42 green
17 mottled
20 yellow
142.7 x 325.4
55 green
21 mottled
24 yellow
142.8 x 325.3
30 green
6 mottled
12 yellow
Totals
198 green
69 mottled
87 yellow
Calculated
199.125 "
66.375 "
83. 5
"
f1.125 "
-2.625 "
+ 1. 5
"
210.1 x 142.5
63 green
18 mottled
20 yellow
326.5 x 115.1
52 green
14 mottled
19 yellow
209.6 x 115.3
27 green
6 mottled
8 yellow
Totals
142 green
38 mottled
47 yellow
Calculated
127.3675
42.5625
56. 75
Deviation
4-14.3125
-4.5625
-9. 75
Deviation
tattled x Yellow
nation of reciproc al totals
340 green
107 mottled
134 yellow
Calculated
326.8125
108.9375
145. 25
Deviation
f13.1875
-1.9375
-11. 25
Analyzing the s e data by the Chi^ Liethod, we h a v e :
(0-C)
Obs.
Calc.
(0-C)
(0-C)2
c
Green
340
326.8125
f13.1375
173.91
.532
Mottled
107
108.9375
-1.9375
3.75
.0o4
Yellow
134
145.25
126.56
.871
Totals
581
581
-11.25
v2
Prom Fisher's tableh“^ J ^
chi square of 1.437 is
A
1.437
that the value of P. for
3 rf£ wh i c h indicates that the theo-
retie 9:3:4 interpretation verj satisfactorily fits the ex­
perimental facts.
Four segregates would be expected, green, mottled, yellow,
end mottled-yellow,
in the F q , but it was impossible to
distinguish between the last two classes,
so all of the
mottled-yellow individuals were classified as yellow.
It will be observed that there are too few of the mottled,
yellow and mottled-yellow classes.
It may be that a larger
proportion of these perished in the seedling stage than of
the green individuals.
were healthy,
Generally, mottled and yellow plants
in the field particularly.
Statistical Methods for Research W o r k e r s .
they reached almost the proportions of normal green plants.
Mosaics, particularly eye mosaics,
are found frequently in
Drosophila melanogaster as a result of X-rays which are ap­
plied to parental cells.
Patterson (1930a, 1930b),
and
Timofeeff-Ressovsky (1929)
induced eye mosaics v/hich were
somatic.
induced mosaic areas in the
Goodspeed (1929)
leaves of Nicotiana tabacum through irradiation, and Stadler
(1930) suggested that In barley chlorophyll deficiencies
v/hich he obtained as a result of X-rays,
least 15/o of mosaics.
consisted of at
lie also reported mosaic endosperms;
he explained their origin as being due to a deletion.
Ii'orlacher (1932), and Horlacher and Killough (1932)
report­
ed that splotched and angular variegations were found in
the leaves of Gossypium h i r s u t u m .
These variations were
undoubtedly due to "abnormal cytoplasmic behavior induced
by X-rays."
Angular variations of another kind seemed to
be due to nuclear changes.
2. Flower Pigmentation.
a. White - It was previously stated that the flower
color of one of the families that was used in this investipigmented
gation had light bluish-violet petals, and a more intensely/
star-eye.
In the second generation after treating 22 soak­
ed seeds of culture T49 with a dosage of 1080 MAM, there ap­
peared a giant plant
(Figs. 9 & 10) which had white flowers.
The giant aspects of this plant will be discussed later;
here we are interested in flower pigmentation only.
the 22 treated seeds, 15 germinated.
consisted of 1R seeds; 15
Of
The control group
of them germinated.
In the
second generation after treatment there were 727 plants
from treated seeds,
and 698 plants from untreated control
seeds.
Kelly (1920)
considered that flower color in the petal of
Phlox Drummondii is due to at least 3 factors.
"The three
factors are conceived to be, first, one that leads to
chromogen formation;
secondly,
production of an enzyme;
one --- , that leads to the
and lastly,
one that leads to the
production of an activator of the enzyme, ---."
Violet flowers,
zyme factor,
then, would have a chromo,_.en factor,
and an enzyme-activating factor.
an en­
Vv'hite flowers
may result from a number of circxmistances in which any one
of the above three factors m a y be absent, the other two be ­
ing present;
of the third;
to a lack of any two of them, and the presence
and to an absence of all three factors.
The white-flowered giant was self-pollinated for a large
next generation, but its fertility was limited.
three seeds developed,
and they were plump, and somewhat
larger than the average seed.
The germination percentage
was very poor, as only one seedling resulted.
ling was very weak,
Thirty-
This seed­
and in a few weeks it was lost,
so
further analysis of this character was interrupted.
Pollen from the giant white-flowered plant was used on
flowers of distantly related control plants which were
light bluish-violet.
In the generation that followed
these crosses, the flowers displayed a more intense p ig­
mentation, a shade near blue-violet.
self-pollinated,
These plants were
and a large crop of seeds developed.
Eut through disaster,
only three plants were produced,
so the situation could not be analyzed further.
Young (1940) reported that through X-rays which were ad­
ministered by the late Doctor J. J. Taubenhaus to Liarglobe
tomato seeds, some white-flowered plants arose.
This
character in the tomato bred true for two generations,
and it behaved as a simple recessive.
b.
Violet Plash - As was indicated previously,
star-
eye of Phlox Drummondli consists of two bars at the throat
of each petal,
and a flash which occupies the center of the
petal slightly distal to the bars.
In the second genera­
tion after treating buds of culture 127a with a dosage of
1041 DAM,
there appeared a plant in a culture of 14 whose
flowers had color only in the flash part of the petal. The
bars of the eye, and other portions of the petal were white.
There was no variation in the intensity of the pigment of
the flash from that of the parent,
and the sibs.
rio
variations were observed among the control material of
537 plants.
Reciprocal crosses were made between the variant and. violetcolored plants of remote relationship.
The distribution of
pigment in the Fg is shown in table X.
Table X - Summary of Fg Progenies of Reciprocal Grosses
Between the Mutation Violet Flash and Light
Bluish-Violet.
342
(flash) x 110 (violet)
35 violet
15 violet flash
346
(flash) x 115 (violet)
23 violet
11 violet flash
118
(violet) x 351 (flash)
41 violet
15 violet flash
121
(violet) x 247 (flash)
53 violet
13 violet flash
Observed
152 violet
59 violet flash
Calculated
158.25 violet
52.75 violet fl.
-G.25 violet
*6.25 violet fl.
Deviation
The deviation divided by the probable error of the ratio I;
1.4-7, which means that the results approach very closely
to theoretical expectation.
Kelly (1920, 1934)
showed that the star-eye of Phlox Drum-
mondii is not transmitted as a unit.
There are genes for
pigmentation of the blade, of the bars,
of which are inherited independently.
and of flash, all
In addition to the
pigment genes,
there is a gene for an enzyme, and an ac­
tivating gene.
In some instances there is a gene for
bluing.
It would seem that the X-rays eliminated the
genes for pigment in the blade and in the bars, or at
least inactivated them.
The genes for the enzyme,
and for the enzyme-activating factor were active, b e ­
cause there was pigment in the flash.
c.
Spinel Pink - A group of 6 spinel pink plants
appeared in the second generation after irradiating 51
dry seeds of culture T51 of the violet-flowered stock
with a dosage of 1275 MAM.
Twenty-two of these seeds
germinated, while 41 of the 45 control seeds were vi­
able.
In this second generation there were 767 progeny
from treated seeds, and 645 plants in the control group.
This character has bred true for five generations,
and
it was confined to the treated plants.
Pollen from three of these mutant plants was used to
pollinate control flowers of the violet stock;
the
flowers of the other 3 plants received pollen from the
same control stock.
All of the offspring of these re­
ciprocal crosses were violet-colored.
Following is a
table (XII) which shows the distribution of pigment in
the second generation.
Table XII - Summary of Fg Progenies of Reciprocal Grosses
Between Spinel Pink and Light Bluish-Violet.
29.3 (sp.pink) x 122 (violet)
61 violet
15 spinel pink
29.4 (sp.pink) x 125 (violet)
53 violet
14 spinel pink
29.5 (sp.pink) x 124 (violet)
43 violet
12 spinel pink
133 (violet) x 29.1 (sp.pink)
29 violet
8 spinel pink
131 (violet) x 29.2
(sp.pink)
31 violet
8 spinel pink
142 (violet) x 29.6 (sp.pink)
27 violet
10 spinel pink
Observed
244 violet
67 spinel pink
Calculated
233. 25 violet 77. 75 sp.pink
Deviation
+10. 75 vblet -10. 75 sp.pink
The probable error of the ratio divided into the devia­
tion is 2.09.
The assumption that the ratio is due to
one pair of genes reasonable fits the data.
When Kelly (1920)
crossed a white-flowered Phlox Drummond!i
with a dark-eyed, white-flowered type, in the F]_ the flower
color was close to rhodamine purple.
segregated.
In the Pg, nine types
"Sight of the types possessed color of some
kind in the flowers and these obviously fell into pairs, one
of each pair being, 'bluer1 than its mate."
Types Ila and lib formed one.
Phlox purple'
in type Ilaj
blade color was about
Among the pairs,
"The color was about
in its 'redder' mate,
'amaranth pink.'"
'light
lib, the
The flower of
type H a
possesses the following genes, a gene,
chromogen factor,
an enzyme factor,
(P), a
(E), the factor A, an
activator of E, and a "hluing" factor,
(B).
Type lib, the
'redder' mate, possesses all of the dominant genes for
flower color,
except the gene for "bluing,"
(B ) .
This spinel pink flower seems to be analogous to the "red­
der" type lib above.
It would seem that the "bluing" fac­
tor was eliminated through X-ray action,
vated.
or, it was inacti­
The transmission of spinel pink conforms to the
findings of Kelly (1920),
"bluing" factor,
(B),
for he demonstrated that the
in Phlox Drummondii behaves as a
dominant.
3. Stature.
a.
viously.
9).
Giant - The origin of this plant was given pre­
It was observed early in the seedling stage (Fig.
The difference in stature between it and its sibs,
and control plants, was quite evident.
As it increased
in age, the difference became increasingly conspicuous, as
figures 9 and 10 indicate.
height of 57.7 cm.
At maturity,
(22.7 inches);
the diameter of the stem
at the surface of the soil was 7.2 mm.
sturdy plant.
it reached a
It was a very
Wo other plant was ever observed among the
thousands of individuals which vmre examined in the progress
of this investigation that could compare with it in size.
Kelly (1915)
states that "there are varieties that are from
12-20 Inches tall", but individuals of the latter propor­
tions, or even approaching them, were not Included in
this study, except this giant mutant.
The giant,
its sibs,
and the control plants, were all greenhouse cultures.
All
of the plants received as near identical environmental con­
ditions as it was possible to give them.
Following is a table which indicates the dimensions of all
of the experimental progeny,
control plants.
same parent.
and a representative group of
Cultures 316 and 372 are offspring of the
Table XXI - Dimensions of Giant, Sibs,
and Representative
Controls.
Number
Relation
Height
Diameter
316.4
Giant
57.7 cm.
7.2 mm.
316.1
Sib
31.3
3.3.
316.2
Sib
32.5
3.5
316.3
Sib
33.6
3.6
316.5
Sib
33.2
3.5
372.1
Control
29.6
3.3
372.2
Control
33.8
3.6
372.3
Control
32.9
3.7
372.4
Control
34.1
3.6
372.5
Control
30.7
3.5
372.6
Control
34.3
3.5
372.8
Control
32.9
3.4
372.9
Control
34.5
3.5
Giant
57.7 cm.
7.2 mm.
Sibs
32.65
3.475 mm.
Controls
32.35 cm.
Averages
cm.
3.4 mm.
The -unusual proportions of giant are not clear.
The offspring, previously mentioned, which were obtained
when pollen of the giant plant was used to fertilize
flowers of normal-statured plants, were not abnormally
large, for 31 plants in the field averaged 31 cm. in
height.
b.
Dwarf - In two instances dwarf plants were p r o ­
duced (Figs. 11 & 12).
Both were very short, and their
offspring, whether they were grown in the greenhouse, or
in the field, were likewise very small.
They were diffi­
cult to handle on account of their short stature.
In
some instances the plants were very weak; other plants
were more sturdy.
Screen door wire covers were construct-
edjto use over them, not only foi' protection from the
weather, but also to guard against cross-pollination.
One of these mutations arose in the second generation
following the irradiation of soaked seeds of T'46 with a
dosage of 735 Mini.
Fifteen of the 2G treated seeds ger­
minated, an d produced mature plants.
control seeds were viable.
Twenty-two of 23
In this second generation there
were 477 plants from treated seeds, and 607 control plants.
The other mutation came from culture 024.5.
given a dosage of 380 IIAm.
Buds were
Thirteen seeds were set f r o m
this treated material, while control branches of the same
plant produced 66 seeds.
irradiation,
In the second generation after
the generation in v/hich this mutation was ob­
served, there were 515 plants from treated buds; the con­
trol plants numbered 407.
Progeny from both of these forms were crossed reciprocally
with unrelated control plants which were normal fox'* height.
All of the F-j_ plants were normal in size.
ing table
(XIII)
acters in the F’2 *
In the follow­
is shown the distribution of these char­
44
Table XXII - Summary of Fo Progenies of Reciprocal
Crosses Between Tall and Dwarf.
<
171.3 (31.4 cm. ) X 426.2
(7.5 c m . )
25 tall
6 dwarf
171.5 (29.5 cm. ) X 426.5 (7.6 c m . )
36 tall
9 dwarf
171.7 (33.7 cm. ) X 426.6
(7.4 cm. )
43 tall
11 dwarf
133.5 (34.5 c m . ) X
84.2
(6.2 c m . )
37 tall
12 dwarf
133.7 (30.4 c m . ) X
84.3 (6.5 c m . )
45 tall
13 dwarf
85.2 (9.2 cm. )
X
155.5 (55.2 c m . )
38 tall
11 dv/arf
97.9 (9.0 cm. )
y
155.5 (35.2 c m . )
9 tall
2 dwarf
97.11 (8.3 cm. ) X 155.7 (31.3 c m . )
10 tall
1 dwarf
97.5 (7.7 cm. )
171.2
(31.3. cm. )
11 tall
3 dwarf
97.12 (9.0 cm. ) X 171.2
(31.1 c m . )
15 tall
3 dv/arf
Observed
267 tall
71 dwarf
Calcula ted
253. 5 tall
34. 5 dw.
Deviation
+13. 5 tall
-13. 5 dw.
The
X
probable error of the r a t i o is 5.37; the deviation di ­
vided by the probable error is 2.51, which indicates that
the simple mendelian interpretation is correct for these
dwarf mutations.
45
The relatively smaller number of dv/arf plants as compared
with the number of normal plants,
was undoubtedly due to
the fact that in general the dwarf plants were weaker,
and
it was difficult to get them started.
Dwarf forms have been
induced in various plants through
rays.
reports a dwarf recessive in Zea
Stadler (1951)
X-
mays, and Horlacher and Killough (1951) record two types
of dwarfs in Gossypium h i r s u t u m .
ultra-dwarf,
dwarf.
One of them was called
and the other was designated as intermediate
Both of them can be recognized early in the seed­
ling stage,
normal,
intermediate dwarf and ultra-dwarf
form a progressive series.
4.
Aborted Flowers - Aborted flowers appeared twice in
the treated progeny of the violet-flowered family.
One
appearance followed the treatment of 22 soaked seeds of
culture T49 which were given a dosage of 1080 LAli. Eleven
of the seeds germinated;
the second generation
there were 15 control plants.
In
after treatment this plant arose,
among 727 plants from treated seeds; there were G98 con­
trol plants in this generation.
The other plant whose flowers aborted arose in the second
generation after irradiating soaked seeds of culture T44
with a dosage of 588 LLAi.i.
Twenty-two of 39 treated seeds
germinated; in the control group there were 27 seeds, and
22 of them germinated..
In this second generation there
were 559 plants from treated seeds, and 637 plants from
The first of these was shorter than its 10 sibs and 15
control plants.
Both the leaves and the flowers were
very small (Fig.13).
The other individual (Fig.14) had
very small flowers and leaves,
and the stem was etiolated.
The anthers and ovules of both plants were small and
shriveled, and contained no viable pollen and ovules.
Through X-radiation,
sterility is produced frequently in
Drosophila m e l a n o g a s t e r , and in other animals.
tations in Zea mays
(Stabler,
1931a., 1931b) show reduced
fertility, and frequently complete sterility.
likewise true of barley.
I.iany mu ­
This is
In both of these sterility may
be due to gene or to chromosomal alterations.
9-oodspeed
(1929a, 1929b) reports that in hi cot fans. tabacum "various
degrees of gametic and zygotic sterility are involved."
4. Lethals - Two instances of physiological sterility
have been presented.; 2 genetic forms will now be discussed.
a. Fifty-six seeds of culture T15 were given a
treatment of 868 UAL.
minated,
not good.
Seventy percent of the seeds ger­
but the seed-setting ability of the plants was
In the next generation the seeds of 7 plants
in a population of 43 plants,
failed to germinate. There
was good germination among the control seeds,
and no seed
losses were observed.
b. Of the 33 soaked seeds of culture T48 which were
treated (981 BIA.Z.I), only 22 germinated.
Seventeen plants
developed, and all of them set a normal quantity of seeds.
But in the following generation,
not germinate,
although the control plants gave almost per­
fect germination,
freely.
the seeds of 4 plants did
and those which were not lethal germinated
Lethals are common among progeny of Drosophila
melanogaster w hi c h have been treated.hy X-rays during some
stage of the life cycle.
Summary and Comclusions:
1. Buds, dry and soaked seeds,
and pollen served as
material for these experiments.
2. Dosages.
A. Unit of measurement - the milliampere-mimute was
the unit of measurement that was employed to calculate
dosages.
B. Materials.
a. Buds - the minimum dosage was 61 MAM; the
maximum, 1168; the interval 2|- minutes.
b. D r y seeds - minimum dosage, 626 MAM; maximum,
2711; interval 5 minutes.
c. Soaked seeds - minimum dosage, 195 MAwI; maxi­
mum, 1705; int erval,
5 minutes.
d. Pollen - minimum dosage, 64 MAM; maximum,
1051 LIAM; interval, 2-b minutes.
e. Pollen - minimum dosage, 65 MAM; maximum,
568 IvIAi.i; interval, 2i minutes.
f • Buds - minim um dosage, 61 IvlAM; maximum, 568
MAH; interval, 2-g minutes.
3. Results.
A. Physiological Results.
a. Many of the treated buds dropped off within a
few days after irradiation.
But many of the buds were
able to withstand the deleterious effects of treatment,
and they set normal seeds in normal quantities.
b. There was a delay of a week or more in the
germination of all treated seeds, dry and soaked.
c. The germination percentages of treated seeds
were lower than that of the control seeds;
the higher
dosages were injurious to the soaked seeds.
d. The seedlings of most of the treated seeds
were stunted, but those seedlings which survived develop­
ed into normal plants.
They set a normal quantity of
seeds which gave as high germination percentages as the
control seeds.
e. When higher dosages were administered, much
of the pollen was inactivated,
tilize many ovules,
but treated pollen did fer­
and normal seed was set.
f. In some instances the X-rays displayed a "di­
rect death-dealing effect upon the seeds."
g. In the Fo albino plants v/ere among the progeny
of a normal plant.
B. Genetical Results.
a. Yellow foliage from green,
a simple recessive.
b. Mottled foliage from green, a simple recess­
ive.
c. v/hite flower from violet-colored flower, poss­
ibly due to chromosomal aberration.
d. Flash from violet-colored flower, a simple re­
cessive .
e. Spinel pink from violet-colored flower, a
simple recessive.
f. Giant from normal stature, probably due to
chromosomal aberration.
g. Dwarf from normal stature, recessive;
appear­
ed twice.
h. Aborted flowers from normal flowers,
i. Lethal,
sterile.
two instances.
Acknowledgements - l.iy sincere gratitude is due Doctor J.P.
Kelly for suggesting the problem, .md for guiding me
through all of its perplexities;
to the Department of
Botany, The Pennsylvania State College,
facilities,
and for a scholarship;
the use of the X-ray equipment,
for the use of its
to Doctor W.P.Davey for
and for technical advice;
to Doctor Harry R.Kiehl for technical assistance;
to Jr.
A.F.Hildebrandt for his advice in growing the plants; and
to my wife, Sllen S.Eangson,
of seeds.
for harvesting the many crops
50
LITERATURE
Collins, G.N. and L.R.Maxwell,
maize seedlings with X-rays.
DeHann, II., 1933.
1936.
Delayed killing of
Science 83:375-376.
Inheritance of chlorophylldeficiencies.
Bibliographia Genetica 10: 357-416.
Goodspeed, T . H . , 1929a.
Cytological and other features of
variant plants produced from X-rayed sex cells of Ni­
cotians tabacum.
Bot.Gaz. >87:563-582.
1929b.
The effects of X-rays and radium
on species of Nicot ia n a.
1930.
J.Tiered. 20: 243-259.
Inheritance in Nicotiana tabacum
IX. Mutations following treatments with X-rays and
radium. Univ.Gal.Bub.Bot.
Goodspeed, T.H.
11: 285-293.
and F.II.Tiber, 1939.
cyto-genetics.
Bot.Rev.
Radiation and plant
5: 1-43.
Henshaw, P.S. and D.S.Francis,
1933.
Growth rate and
radio-sensitivity in Triticum vul,gare .
Comp.Physiol.
Horlacher,
4: 111-122.
,;.R., 1932.
Production of invitations in Ameri­
can upland cotton by radiations.
tics 2: 37-90.
Jour.Cell. 5;
Sixth Int.Gong.Gene­
51
Horlacher, W.R. and D.T.Killough,
variation in cotton.
1931.
Radiation-induced
Jour.I-Iered. 22: 253-262.
1932.
Chlorophyll defi­
ciencies induced in cotton (Gossypium h i r s u t u m ) by ra­
diations.
Trans.Tex.Acad.Sci.
15: 33-30.
1933. Progressive m u t a ­
tions induced in Gossypium hirsutum by radiations.
Am.Hat. 67: 532-538.
Johnsom, E.L., 1931.
Effect of X-radiation upon growth and
reproduction of tomato.
Kelly, J.P., 1915.
Plant Physiol.
6: 685-694.
Cultivated varieties of Phlox Emmmondii
Jour. N.Y.Bot.Garden 16: 179-191.
1920.
The genetical study of flower form and
flower color in Phlox D rummondli.
1934.
Genetics 5: 189-248.
The "eye11 of Phlox.
Jour. He red. 25:
183-186.
Lambert,
J . , 1933.
Recherches sur les factairs be la radio-
sensibilite tissulaire en dehors des phenomenas morphologiques.
Les proprietes biologiques des tissus ietents.
Archiv.Biol.
44: 621-739.
MacArthur, John W., 1934.
Jour.Hered. 25: 75-78.
X-ray mutations in the tomato.
m
Matsuura, Hajimem 1933.
genetics.
A Bibliographical monograph of
Asppor,
Iloore, C.N. and C.P.Haskins,
1935.
X-ray induced modifica­
tion of flower color in the petunia.
Jour.Hered. 26:
249-355.
'duller, H.J.,
1930.
Radiation and genetics.
Am.Nat.
64:
1934.
Radiation genetics. Quart.Rev.Biol.
220-251.
Oliver, C.P.,
9: 381-408.
Patten, Ruth E.P.
on seeds.
and S.B.Widoger, 1929.
Effect of X-rays
Nature 123: 606.
Ridgway, R . , 1912.
Color standards and color nomenclature.
Washington, D.G.
Stadler, L.J., 1928.
Genetic effects of Z-rays
in 'maize.
Proc.Nat.Acad.Sci. 14: 69-75.
19285. Nutations in barley induced by X-rays
and radium.
Science 68: 186-187.
1928c. The rate of induced imitation in re­
lation to dormancy,
temperature and dosage.
Anat.Rec.
41: 97.
1930.
plants.
Some genetic effects of X-rays in
Jour.Hered.
21: 3-19.
Stadler, L.J., 1931a.
The experimental modification of
heredity in crop plants.
gularities.
Sci.Agr.
I. Induced chromosomal irre­
11: 557-572.
II. Induced mutation.
Sci.
Agr. 11: 645-661.
1932.
On the genetic nature of induced
mutations in plants.
Proc.Sixth Int.Gong.Genetics
1: 274-294.
Timifeeff- Ressovsky, N.V/., 1929.
The effect of X-rays
in producing somatic genovariations of a definite locus
in different directions in Drosophila melanogaster.
Am.Nat.
63: 118-124.
Young, P . A . , 1940.
White-flowered character from X-rays
treatment of tomato seed.
Jour.Hered. 31: 78-79.
Figure 1. - The plant on the left (a) is a representa­
tive of family 2; the flowers are tyrian pink, and th
star-eye is more intensely pigmented.
right (b) represents
family 1.
The plant on t
The flowers are light
bluish-violet with a more deeply colored star-eye.
it
r
Figure 2. - The machine which, was used in administer­
ing the X-rays to the experimental material.
Figure 3. - These seedlings illustrate the effect of
X-rays upon germination.
The seedlings on the right
(b) are from dry seeds whic h were given a dosage of
2209 FIAX.
Those on the left (a) are controls of the
same age.
The picture was taken 29 days after the
seeds were sown.
mVmik
feNSw
Bill
i ^
l l l
lr%>M
X* --;•$!-t
w A'^4
V
.^
<*f
?
>*,»V
Figure 5. - Showing the effect of X-rays upon growth end
development of some of the first leaves.
The leaves on
the right (b) are from seedlings whose seeds were given
a dosage of 626 MAX.
The leaves on the left (a) are
from control plants.
All of these leaves were taken at
the same level.
'■"
■
•
„
m
Figure 6. - iere are some of the _abnormal shapes assumed
b;; a few of the first leaves of seedlings from treated
dry seeds.
The T25A plants are from seeds which were
given a dosage of 626 MAM.
The T165.1 plant came from
a dry seed..- which was given a dosage of 1684
I
:21.9
. 13
I
Figure 7. - Deformed first leaves of plants from t reated
dry seeds.
shape.
Future leaves were normal in size and in
The T21 series received a dosage of 2209 -.i/i.a )
that given the T22 plant was 2309 lift.:.:.
Figure 3. - The plant in the upper left (a) is mottled.
It arose in the second generation after 'treating dry
seeds with a dosage of 1634 nAII.
(b) is yellow.
In the foreground
It was first observed in the second
generation after irradiating dry seeds with a dosage
of 1574
normal plant.
The plant in the upper right
(c) is a
Figure 9. - The giant plant (b) arose from soaked
seeds which had been irradiated with a dosage of
1080 MALI.
The plant on the left (a) ’is a sib of
the giant plant;
control plant.
the plant on the right (c) is a
^7!
V
,•
'
4
••
-
Xj. ' A
*«» 2 ’'■,i
;sS5?*SS**
«&•
—’*f?
‘’igure 10. - The giant (b) is in the center,
the left,
sib (a) on
and control (c) plant on the right.
This
picture was taken 16 days after the picture which is
figure 9.
Figure 12. - The plants at the left (a) are dwarf
mutations;
sib.
the plant at the right (b) is a normal
The dwarf plants came from treated buds
which were given a dosage of 380 I.IAM.
igure 14. - Aborted flowers.
small,
The leaves are very
and the stem is etiolated.
This plant arose
from a soaked seed which had been given a dosage of
588 SIAM.
See 'figure 15 for a control plant.
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