E F F E C T S O F MACERATION AND DRYING UPON THE V E R T E B R A L COLUMN T. W I N G A T E TODD AND S. I D E L L PYLE Anatomical Laboratory, Western. Beserve University, Cleveland, Ohio ONE CHART CONTENTS Introduction and methods ............................................ Material and the vertebral curves ...................................... Precision of measurement ............................................ The shrinkage of cancellous tissue on drying ............................ The analysis of vertebral shrinkage ................................... Final statement of the problem ....................................... Summary ........................................................... Literature cited ..................................................... 303 306 308 311 313 315 318 319 INTRODUCTION AND METHODS Detailed and accurate measurement of defect is more important in dealing with disability in the vertebral column than in treatment of any other p a r t of the skeleton. But as the bones of the column are, f o r the most part, deeply placed in the body, the only practicable method of obtaining information is the roentgenogram. To derive dimensions of the actual vertebral bodies from measurements on the roentgenogram is our chief aim. But since we may study the column itself, as a rule, only upon the dried macerated skeleton it is equally necessary to discover the relation of the macerated dimensioiis to those of the fresh or ‘green’ bones. The senior author has already set forth in detail the shrinkage in skull dimensions consequent on maceration and drying(2). Ingalls has dealt in similar manner with the femur as a representative of the long bones, arid also with the ribs, scapula and other bones(1). The vertebrae form a class by 303 AMERICAN JOURNAL O F PHYSICAL .4YTHROPOLOOY. VOL. XII, NO. 2 OCTOBEU-DECEMBER. 1928 304 T. WINGATE TODD A R D S. IDELL PYLE themselves and must be separately and intensively studied. To this end we have applied ourselves and our results a r e presented in this communication. Since the vertebral bodies a r e largely composed of cancellous tissue the problem differs somewhat from those previously undertaken and the period of shrinkage is greatly lessened. To assure ourselves of technical precision it is necessary to provide check determinations and hence we have adopted four methods of measurement. All are vertical dimensions and are comprised in the following. Method I. Ventral vertical diameter. This is measured by sliding calipers directly upon the thoracic and lumbar bodies but on the cervical bodies it is necessary to place the limbs of the instrument in contact with upper and lower surfaces of the body. Hence the height is a projected measurement and is less than the direct determination. Nethod 11. Mid-centrum vertical diameter. The instrument used is the bow calipers of the Flower craniometer type though spreading calipers would do. We have chosen the former f o r greater ease in determining fractions of a millimeter for on the Flower instrument the divisions a r e actual millimeters and not progressively changing fractions of a millimeter a s they must be on spreading calipers. Moreover, spreading calipers except those manufactured in this laboratory, appear to have the fractions determined by a kind of interpolation of assumed value and hence cannot be depended upon throughout the range of the instrument. The R,eserve spreading calipers a r e calibrated by mathematical computation upon a lead screw. Although this instrument is accurate i n all parts of its range the divisions are too small to enable fractions of a millimeter to be sufficiently accurately judged for our present purpose. There is frequently an ifregularity in the upper surface of the thoracic and lumbar vertebral bodies, either an elevation or a depression, about the center of the surface. Method IT avoids this irregularity and the measurement in practice is usually made immediately dorsal t o the uneven area. EFFECTS OF MACERATION A N D DRYING 305 Method I11 was intended as a determination of postcentral vertical height. It was taken by sliding calipers one limb of which was laid along the upper surface of the vertebral body. The lower limb was then drawn u p to contact with the point on under surface most distant from the upper surface. The scheme was planned to measure the maximum height of centrum wherever found. I n practice the method proved uiireliable since true maximum height is often vitiated by a raised irregular ar ea on upper surface of body and by temporary irregularities occurring on the cancellous surfaces during drying. Method I11 was therefore given up and the records eliminated from this report. Method IV. Dorsal vertical height. Flower’s craniometer. This is the over-all dimension of the body at the floor of the vertebral or spinal canal. I t was expected that Methods I and I V would check each other and measure the thin shell of compact tissue on ventral and dorsal surfaces of the body. Methods I1 and I11 were also planned to check each other and determine the value of the cancellous tissue dimension of the vertebra. I n practice this did not happen. Method I11 became obsolete and method TV turned out to be a check on Method I1 and not on Method I. Examination of our final results (Table V I ) demonstrates this quite clearly and indicates that the shell of compacta on the floor of the spinal canal does no more, in our data, than act as a regulator of shrinkage of cancellous bone without affecting its total extent. It is but a glaze upon the cancellous tissue, nothing more. The senior author and Doctor Ingalls agree that there is no warping of a bone on drying after maceration comparable to that which occurs in wood. The warping certainly found in exhumed bones must be laid to other causes than simple drying. Nevertheless both authors also agree that compact tissue shrinks much more slowly than cancellous tissue but the bones upon which they worked gave no data for determination of the relation between the shrinkages of these two forms of osseous tissue. One of the secondary issues of the present work is the elucidation of this subsidiary problem. 306 T. WI NGATE TODD AND S. IDELL PYLE MATERIAL AND THE VERTEBRAL CURVES The material upon which our work is based consists of 106 vertebral columns divided into three series. The first series consists of 10 columns of which flat lateral roentgenograms were taken before maceration. The second series comprises of 71 columns upon which the vertical dimensions of the discs were determined in the fresh or green stage before the columns were macerated. There a r e no roentgenograms of this series. The vertebral bodies, being already macerated and dried when our work commenced, had to be soaked t o restore the original green dimensions. That this actually occurs may be inferred from Todd’s work on the skull(2). The third series includes 25 columns on which stereoscopic anteroposterior and lateral roentgenograms were taken before maceration. These columns were obtained wet from the macerator and measured during drying. I n all columns the direct height is known. This determination is made by the Stangenzirkel, one limb of which is placed on the upper border of the ventral arch of the atlas or the tip of the odontoid process of the epistropheus, the other on the ventral upper lip of the sacral promontory. Since the cervical, thoracic and lumbar curves differ from column t o column this dimension bears a varying relationship to the composite measurement which is the sum of all ventral vertebral body heights and disc heights on the specimen. To illustrate this, Table I has been prepared. The composite column height is obtained by adding together the wet body heights and green disc heights. From this the atlaspromontory length is subtracted and the difference is expressed as a percentage of the atlas-promontory length. As a rule this percentage varies between 1 and 3. Examination of the lateral roentgenogram shows slightly marked curves in all regions though in No. 1207 it is stated that the thoracic curve was greater than usual. I n No. 1145 the thoracic curve was marked and the percentage 8.4; in No. 1210 both thoracic and lumbar curves were marked yet the percentage amounted to but 5.4. I n No. 1227 with no marked curves the percentage 307 EFFECTS OF MACERATION A N D DRYING is 5.3. W e have examined the records to pick out bedridden cases with their exaggerated thoracic and cervical curves but this gives us no help. So, f o r the moment, we a r e baffled and can but state that 011 the average, 3.0 per cent added to the atlas-promontory length will give the approximate sum of the composite heights of bodies and discs. It must be very clearly understood that this refers only to our cadaveric material under observation and must on no account be transferred to living individuals. The curvatures of the column change with death. Although there is but little difference TABLE I Composite column height and atlas-promontory length Skeleton number 1 1114 11145 I 1 I I 1 11133 1097 1179 1205 1227 __ __ 1207 1201 1310 -- 1. Sum of heights of soaked bodies (method I ) 2. Sum of heights of green discs 3. Total composite column height 4. Atlas-promontory stangenzirkel dimension 5. Difference (3-4) 6. Percentage of 5 011 4 540.0 493.0 147.5 144.5 687.5 637.5 682.0 605.0 5.5 32.5 0.8 5.4 ~ between sitting height and stem length in the living there is a profound distinction between living sitting height and dead stem length. Since o u r observations a r e certainly inadequate for transference from the latter to the former we a r e driven to the only alternative, namely the measurement of actual dimensions of living vertebrae by roentgenographic methods and the correlation of these with living sitting height. A piece of collateral evidence which will be fully presented in another communication, but is of considerable suggestive importance in the difficulty here presented, is illustrated by our measurements of stature in children. Whereas the aver- 308 T. WINGATE TODD AND S. I D E L L P Y L E age heel height was 10 mm., the difference between the average stature, shod and unshod, was 25 111121. This of course means that the raising of the heels results i n reduction of spinal curvature to a relatively high degree. PRECISION OF MEASUREMENT I n a problem which involves the summation of many separate measurements of relatively small dimension it is quite necessary to establish the precision of technique. We need to know how closely remeasurement of the column will approximate the original figures whether of the same or of another observer. Table I1 gives evidence on the former count. Miss Pyle measured the composite heights of four columns by methods TABLE I1 (Z.P.) Repeated measurement of column i n millimeters I _ _ _ Method I A. Skeleton Dried composite column height: 1st observation 2nd observation Difference Average difference B. Skeleton Dried composite column height: 1st observation 2nd observation Difference 1 ~ 1066 ___ 430.5 432.5 2.0 1188 1215 1080 484.0 483.0 1.0 444.5 446.5 2.0 471.0 472.0 1.0 1215 1080 416.0 418.0 2 .o 439.0 439.5 0.5 i 1066 1 _______- 375.5 373.5 2.0 C. Eight skeletons (see table IIIc) Method I (i) Measured dry (G) Soaked: dried 18 days: measured (iii) Measured 7 days a f te r (ii) Average differences between i and ii, 6.0 mm. i and iii, 8.6 mm. ii and iii, 2.6 mm. Average of these differences, 5.7 mm. ~ 1188 442.5 442.5 0.0 [ EFFECTS O F MACERATION AND DRYING 309 I and 11. Later, after the measurement of some sixty other columns so that memory might be confused, she remeasured these four. The average differences are only 1.1mm. and 1.5 mm. respectively on the entire column. This evidence which looks so satisfactory is precisely the kind of evidence which gives a false sense of security f o r it is based on the results of a trained observer consciously checking herself. Table I I C gives a more truly representative indication of reliability for, as explained in the table, procedures were carried out between measurements which threw out of mind all possible conscious relationship of measurements with the consequence that the true average difference is about 6.0 mm. Of course, in making Table IIC we have been careful to utilize measurements made when the bone dimensions were really comparable. This is explained in the chapter on shrinkage in drying. The average diffcrence of approximately 6.0 mm. per column indicates an average difference of 0.25 mm. per vertebra. This is the same observational difference which we shall find characteristic of the results of successive observers. It is the maximum possible precision of reading unmarked fractions of a millimeter. The problem of the second observer is of course f a r the more important and we therefore present a extended check upon this count. Table I I I A gives the composite column height in two skeletons measured by Miss Pyle and myself according to Method I. The average difference amounts to 6.3 mm. Appended to this is Table I I I B, which, by method IV. gives an average difference of 1.5 mm. We believe that the former difference of 6.3 mm. is a closer probable value and that the difference of 1.5 mm. is a fortunate accident. Tables C and D show the results of measurement of the 17 thoracicolumbar vertebrae and of the 7 cervical vertebrae respectively. The differences of 4.4 mm. for thoracico-lumbar and 1.7 mm. f o r cervical, together with the 6.3 mm. of Table I I I A, indicate that the difference between the determinations of two observers depends upon the number of observations made and summated rather than upon the absolute values of the dimen- ~ - - _ ~- I I 98.0 95.0 3.0 _ _ 1133 _ ~ _ 1.5 _ 1 - ~ 364.5 361.0 3.5 __ 1207 564.5 563.5 1.o ~ I 1 1201 90.5 89.5 1.0 - I ~ - 1210 ~ Average 1.5 mm. I l l _____-__ -~ 428.5 384.5 433.5 382.5 5.0 2.0 ______ 1201 __- I -___ Average 6.3 mm. I I -1 I 1179 __- I I _ _ 108.0 105.5 2.5 ~- ~ 99.0 98.0 1.0 ___ ..__.___ 1227 _ I _ - 94.0 97.5 3.5 111.5 110.5 1.0 .__ 1205 - I 1201 107.5 107.5 0.0 93.0 96.0 3.0 87.0 93.0 6.0 - ~ . _ _ _ _ 108.0 107.0 1.0 ____ 1207 92.5 91.0 1.5 ___ - 110.0 109.5 0.5 __ _ 1210 __ ~ _ ~ _ _ _ _ _ - - . _ _ - _ _ 1227 ~ ___ 385.0 381.5 3.5 _ 4.5 467.5 463.0 1133 99.5 120.5 102.5 98.0 119.0 105.0 1.5 --__ _ _ _ 1.5 _ _ 2.5 I -1097 __ 1 _ 1205 _ 375.5 367.5 8.0 _ _ _ 1179 _ 358.0 360.0 2.0 _ 1 I l l -___- ~ _ _ - _ _ - _ _ 114.5 115.5 1145 _ _ I _ _ ________I _ 96.0 100.5 4.5 _ _ _ _ _ _ _ _ ^ _ -_____ ~ I I _ 1097 ____ 348.0 340.0 8.0 _ ~ _ _ 1114 _ _ _ _ _ _ ~ ___I__ ~~ ___ E. Skeleton Cervical oiily. T.W.T. Cervical only. I.P. Difference Average 2.4 nim. 1 I 388.0 355.0 3.0 - 1145 503.0 505.0 2.0 1179 I _-__ ~____ ~ I____-__ Cervical only. T.W.T. Cervical only. I.P. Difference Average 1.7 mm. -_____ _ _ __ D. Skeleton Average 4.4 mm. __-____ _ T.W.T. I.P. 1 1 0. Skeleton Thoracico-lunibar only. Thoracico-lumbar only. Difference ~- 1 ~ R. Skeleton Composite height dried bodies I.P. Composite height dried bodies T.W.T. Difference -____ ___-___~ 423.0 431.0 8.0 - 1114 - _ _ _ _~ ______ _ _ I _ _ A. Skeleton Composite height dried bodies I.P. Composite height dried bodies T.W.T. Difference Composite heights TABLE I11 E F F E C T S O F MACERATION A N D DRYING 311 sions measured. I n other words the difference in column length is really the difference in reading the fractions of millimeter which must be estimated on the instrument. A check of method I1 on method I is set forth in Tables IT1 D, E. The evidence brought forward enables us to state with confidence that measurement of vertebral body height can be made by different observers with sufficient accuracy and read with precision enough to permit comparison of results. I n comparing the records of different observers, however, it is wise to allow a possible individual difference in reading of 0.25 mm. per observation recorded. I n any anthropometric data this is, indeed, the maximum accuracy attainable. THE SHRINKAGE O F CANCELLOUS TISSUE ON DRYING To investigate shrinkage on drying we adopted the methodfollowed by Todd on the skull, namely the investigation of successive samples, thereby eliminating discrepancies due to variations in atmospheric conditions with change of season, artificial heat in the Institution, and dampness due to forcing washed air through the building in the absence of artificial heat. W e took the first series of 10 columns, measured them dry, soaked them, measured them again, dried them at atmospheric temperature and measured them during drying. Later we obtained the third series of 25 fresh from the macerating tank and measured them also during drying. The first essential is knowledge of the drying period of a vertebra, during which shrinkage occurs. F o r the skull this is about 28 days at atmospheric temperature and moisture; for the femur it may be 18 months. The length of time depends on the absolute thickness of compact tissue. There is very little compacta in vertebrae, practically none in measurements by method 11. B y method I1 we may therefore investigate the period of shrinkage of cancellous tissue in drying. Now of the 10 columns, one, No. 1097, is that of a Negro male aged 18 years. The partially ossified and as yet ununited epiphyses of this column warped on drying as such 312 T. WINGATE TODD A N D S. I D E L L PYLE epiphyses always do. This vitiated the shrinkage records and the specimen is therefore eliminated. No. 1179, a male IVhite of 35 years, developed, in the third week of drying, local convexities on the upper surface of the thoracico-lumbar bodies. Hence it also had to be eliminated. With two columns discarded the remaining eight are reliable as a series for use. By Table IV the average shrinkage, per column, during the first week is 8.0 mm., during the second week 4.3 mm., and during the third week 0.12 mm. Clearly then the drying period of cancellous tissue at room summer temperature is about 14 days. This is confirmed by the oscillatory change TABLE IV Shrinkage of cancellow tissue. 8 columns: Method XI xm. 1. 2. 3. 4. 5. 6. 7. 8. 9. Total wet length Total shrinkage 0-6 days Total shrinkage 7-13 days Total shrinkage 14-25 days Expansion between 26 and 50 days Total dry length 25 days Total dry length 50 days Percent of 4 (cumulation) on 6 Percent of 5 (cumulation) on 7 (CUMULATION) 3554.0 444.25 63.5 34.5 1.0 4.0 3455.0 3459.0 2.86 2.74 AMEAOE 8.0 (98.0) (99.0) (95.0) 4.3 0.12 0.5 431.9 432.4 setting in during the fourth week, resulting in an average expansion of 0.5 mm. Now the total amount of shrinkage equals 2.7% of the final summated dry length. It greatly exceeds the shrinkage of the skull and far outdistances that of the femur. On the average the shrinkage in a bone has been found t o amount to about 1% of the dried length. It is conceivable that the greatly increased shrinkage in the vertebrae may be due to the fact that method I1 measures cancellous tissue shrinkage alone. One must also make the reservation that the discrepancy might be an artefact due to errors of measurement and reading. Obviously further investigation is necessary. EFFECTS O F MACERATION A N D DRYING 313 THE A N A L S S I S O F VERTEBRAL SHRINKAGE So unexpectedly great was the shrinkage of the trial sample of mixed columns just recorded that we have taken u p the problem in greater detail. Series I and I11 together contain thirty-five columns. But of these fifteen had to be discarded in this particular phase of the study since readings upon them were vitiated by the presence of warping epiphyses or by the occurrence of fusion between successive bodies, or because of some deficiency in record. Very galling it was to find, after weeks spent in laborious measurement and remeasurement, that many columns must be disqualified by a single fusion between two successive vertebrae. The twenty remaining however constitute a series of quite reliable character. Of these one half were male Whites, one quarter male Negroes and of the rest two were female Whites and three were female Negroes. These four groups were segregated and their shrinkage studied separately. The total shrinkage in twenty-five days of drying is set forth in detail in Tables V and V I and the successive stages in drying are shown in Graphs. There is an erratic character in the shrinkage especially of the pure cancellous tissue as demonstrated by method I1 but the final results, allowing for discrepancies in numbers, a r e unexpectedly harmonious. Since the number varies so greatly from group to group it is necessary to weight the average values. This is done by multiplying the average of each group by the number in the group, adding the values thus obtained and dividing the resulting sum by the total number of cases. I n this manner Table V I has been prepared. The probable shrinkage of the ventral face of the vertebra averages about 1.5% of the final dry dimension whereas the shrinkages of both the central part of the body and the dorsal margin a r e about 2.5% of the final dr y dimensions. As a test of these conclusions we investigated certain columns originally in Series I but eliminated therefrom before the series was amalgamated with Series I11 f o r the con- 314 T. WINGATE TODD AND S. IDELL PYLE struction of standard shrinkage tables. Of these columns there were eight, namely two male White and six male Negro. Total wet and dry dimensions, summated for the entire eight, were obtained by methods I, I1 and IV, and from these figures the differences between wet and dry totals were converted into percentages of the summated d r y totals. The TABLE V Percentage on total ?*aktes Slirinkage b y days. ~ I ~~ 0.6 1 7-13 1' 14-18 IMethod I Male White average Male Negro Female White Female Negro 0.92 1 1 19-25 I 0-25 \ l____l ' 0.29 0.78 0.10 0.19 0.17 0.04 1' j 1.40 1.50 1.58 1.80 1 2.38 2.34 3.26 2.66 Method I1 Male White average Male Kegro Female White Female Negro -- Male White average Male Negro Female White Female Negro -_ 1 0.68 1.67 1.47 1.73 I I ! 1 1.64 1.65 I +0.14 0.38 :::; 1 0.43 I 0.16 0.95 0.25 0.09 0.94 0.39 1 ___-- I I 0.55 0.67 0.28 I :::: 1 0.19 1 _. 1 0.05 0.08 0.17 +0.19 2.44 2.76 2.53 2.29 - results a r e : method I, 1.59% ; method 11, 2.87% ; method IV, 2.38% (See Table V I I ) . These figures approximate our st,andard shrinkage results closely enough to give us confidence in applying our standard figures to vertebral shrinkage in general. It must be understood that these eight columns a re the initial samples used in Table I V but eliminated from the standard series because there is no record of their being measured on the eighteenth day of drying. 315 EFFECTS OF MACERATION A N D DRYING F I N A L STATEMENT OF THE PROBLEM I n this study of shrinkage on drying after maceration the problem has been complicated by the fact that we a r e not TABLE VI Summary of Series I and 111 RACE A N D SEX NUMBER i PERCIINTAQE O? BHEINXAQE IN 25 DAYS I _ I _ i WEXOHTED AVERAQE I N PERCENT I Method I Male White Male Negro Female White Female Negro -_ I 10 5 i 1.4020 1.5005 1.5801 1.8008 t 14.02 7.50 3.16 5.40 _____I_____ Total Average 20 -I__.__ ___ hlale White Male Negro Female White Female Negro Total Average Method I1 10 j 2 3 I 20 I 30.08 1.50 - __I 2.3800 2.3378 3.2602 2.6564 ~ -1 23.80 11.69 6.52 7.97 49.98 2.50 Method I V Male White Male Negro Female White Female Negro -_Total Average 1 , .- i I -. 20 ..-__ 24.49 13.82 5.06 2.4492 2.7631 2.5309 2.2936 10 5 2 3 I- --- - -1 50.25 2.51 __ _. I _ _ I measuring the shrinkage of a single bone but of a series of bones. Further, owing to the flexibility of the column, summation of measnrements bears no constant relation to the articulated column length. It has been necessary therefore to embark upon a long and careful investigation of the simple MYSO 18 25 482 4.2 Y 460 4SB 467 467 u7 445 444 444 4 s 415 4x5 45 429 429 423 420 419 u? 492 492 6 13 METHOD ONE WW 404 p METHOD TWO F W 412 METHOD FOUR 493 r w 456 DAYS 0 44s 444. 4 4% 435 436 13 6 18 25 Chart 1 Shrinkage on drying of vertebral columns. Shrinkage completed in three weeks, almost completed in fourteen days a t room temperature. There is a humidity oscillation as in other bones. Method I, ventral body height. Method 11, mid-centrum diameter. Method IV, dorsal body height. 316 317 EFFECTS OF MACERATION AND DRYINQ technique of measurement before we could proceed to our proper object. The results of this iiivestigatioii a r e set forth above. Next, the observatioiis on duration and extent of shrinkage show that the vertebral column requires treatment by itself, for, unlike the majority of the skeleton, its constituent bones are built almost solely of cancellous tissue. The ventral face, with its average shrinkage of 1.5% of the dried measurement, TABLE VII Percentage shrinking of the 8 columns Method I i'1 Method I1 )RY 25 DAYS WET Method I V DRY 25 DAY WET )RY 25 DAYS _ _ ~ - _ _ 1114 coL. 1145 1133 1205 1227 1307 1201 1210 Total 1 1 1 1 420.0 WET 501.5 460.5 475.5 495.0 469.5 540.0 493.0 3855.0 Difference Percent on dry 418.5 493.0 456.5 468.5 489.0 460.0 524.0 485.0 384.0 484.5 404.0 479.0 444.5 426.5 498.5 433.0 3794.5 3554.0 -- 378.0 4i7.0 397.0 452.0 436.5 410.5 484.5 419.5 447.5 532.0 474.0 492.0 515.0 483.5 566.5 513.0 429.0 522.0 466.5 480.0 504.5 472.0 556.5 499.5 3455.0 4023.5 3930.0 -- 60.5 99.0 93.5 1.5944 2.8654 2.3791 -~ _ _ I _ Pu'one of above by methods I, 11, I V included in the standard series of shrinkage made up from series I, 111. approximates most closely to the general rough average for bones, namely 1.0%. But measurement of the mid-centrum diameter and of the dorsal face shows in each a shrinkage of 2.5% of the dried dimension. Because of the extraordinary and complex change on drying, dimensions on the dried column cannot be used uncorrected as a basis for consideration of the vertebral column during life. But this difficulty fades into insignificance compared with the greater complexities of inter-vertebral discs and spinal curves. These must be treated separately in a AMERICAN J O U R N A L O F PIfYSICAL ANTHROPOLOOY. VOL. SKI, NO. 2 318 T. WINGATE TODD AND S. IDELL PPLE further communication. Since our preliminary experiments indicate that there can be no simple solution of the problems of discs and curves, and since the very measurement of the dried vertebrae is attended by exceptional difficulty we believe it more hopeful to attack the problem of vertebral dimensions from the roentgenographic standpoint. Naturally the foregoing strictures have reference only to the problem of the vert,ebral centrum. So far as articular processes a r e concerned there is no necessary confusion between living and dried values and inter-relationships since changes on drying must be extremely slight and there is no warping during drying. SU M MA RP 1. Determination of changes in the vertebral column produced by maceration and drying is attended with difficulty inasmuch as the column is a series of small bones, each of which must be measured separately. 2. Ileasurements and remeasurements, whether by one or more observers, cannot have a greater precision than the nearest 0.25 mm. which is the error of observation on a millimeter scale. I n a presacral column of twenty-four vertebrae this observational leeway is 6.0 mm. 3. Shrinkage determinations, preferably carried out by a single observer, show that there is very slight shrinkage of vertebral bodies after fourteen days drying and that a period of three weeks covers the entire process of shrinkage. 4. Shrinkage of the vertebral centrum is unequal. It amounts to 1.5% of the dried dimension in the ventral body height, 2.5% of the dried dimension in the mid-centrum diameter and the dorsal body height. These discrepancies a r e apt to result in temporary irregularities of upper and lower surfaces although as in other bones, no evidence of warping can be found. 5. The unequal amounts of shrinkage in the several parts of the centrum, together with the difficulties introduced by intervertebral discs and spinal curves indicate that actual EFFECTS O F M A C E R A T I O N A N D D R Y I N G 319 dimensions of the vertebral column in life can probably be more precisely determined from the lateral roentgenogram. 6. The results of shrinkage, a s exemplified in different small samples, a r e harmonious enough to justify the application of our standard figures to vertebrae in general. LITERATURE CITED 1 INGALLS,N. W. 1927 Studies on t h e femur. 111. Effects of maceration a n d d r y i n g i n t h e W h i t e and Negro. Am. J. Phys. Anthrop., X. 29 7-32 1. 2 TODD,T. W. 1923 T h e effect o f maceration a n d d r y i n g upon t h e linear dimensions of t h e green skull. J. Anat., L V I I , 336-356. 1925 The n a t u r e of mummification a n d maceration illustrated by t h e male W h i t e skull. J. Anat., L I X , 180-187. 1926 The n a t u r e of mummification a n d maceration. 11. Female and N e g r o skulls. J. Anat., L X , 309-328.