Showing papers in "American Journal of Physical Anthropology in 1968"

The use of metallic implants in the study of facial growth in children: method and application.

Abstract: On the basis of experience gained over a number of years, an account is given of the technique for insertion of the implants, the radiographic method, and the graphic procedure for preparation of growth tracings. Small pins of hard tantalum are hammered into the bone under local analgesia with a pencil-shaped instrument, in the tip of which the implant is placed. No surgical exposure is necessary. Because of remodeling resorption of the bone and eruption of the teeth, the implants can be placed only in certain places in the maxilla and mandible. In implant studies it is necessary to observe a high level of reproducibility in positioning the head in the cephalostat. An X-ray cephalostat with a built-in image intensifier has been designed which enables the position to be monitored by televison. In the graphic procedure, drawings of the arches from dental casts are incorporated in tracings of profile radiographs; the paths of eruption of the teeth and development or the arches can then be examined with the metallic implants as references.

Description and classification of degenerative bone changes in the distal joint surfaces of the humerus

Abstract: This paper attempts to provide the descriptive and classificatory basis for a clearer understanding of degenerative changes on the humeral elbow. Two general problems are outlined. One in the study of the elbow as an indicator of stress in making comparisons between populations. Preliminary data on two series, Alaskan Eskimos and Peruvian Indians, indicate a much higher incidence among the Eskimos (18% as compared with 5% in the Peruvians). The second problem results from the unique morphology and function of the elbow. Mechanical stress on the humeral elbow is fairly evenly distributed over the entire surface of the trochlea in contrast with the capitulum where stresses are localized away from the edge in approximately the geometric center of the capitulum. Hypertrophic bone formation is much greater on the periphery of the trochlea where mechanical stress is frequent than on the edge of the capitulum where mechanical stress is infrequent. This observation supports the generalization that local stress is an important factor stimulating the formation of hypertrophic bone.

Climatic influence on the skeletal nasal aperture

Abstract: Climate is thought to be one of the factors affecting the distribution of nasal form as represented by the breadth and height of the skeletal nasal aperture. A model of nasal function is developed to predict influences on the skeletal nasal dimensions by selection acting upon the external nasal passage and aperture. Cranial series from Alaska and Australia, each series representing a climatic continuum from warmer and moister conditions to cooler and drier conditions, verify the predictions. These data suggest conditions for testing hypotheses about human variation.

Transverse lines in long bones of prehistoric California Indians.

Abstract: Radiopaque transverse lines (lines of arrested growth, Harris's lines) were counted on X-rays of the distal end of 102 adult femurs from prehistoric California Indian populations representing three archaeological Horizons. The sample from Early Horizon has the highest frequency of lines, the Middle Horizon the next, and the sample from Late Horizon has the lowest frequency of lines. These differences are statistically significant. Archaeological evidence indicates that the Indians improved and broadened their subsistence economy from Early to Late Horizon. It is concluded that the differences in the frequency of lines among the three California Indian populations probably are associated with differences in morbidity and/or nutritional status of the people. If this hypothesis is correct, then frequency distribution of transverse lines represents a valuable tool for the paleopathologist and the archaeologist.

The size and morphology of the Nasioi dentition.

Abstract: Dental impressions were obtained on 240 Nasioi, a Melanesian population living on the island of Bougainville. Odontometric data are presented for both the permanent and deciduous teeth, and the former teeth are also examined morphologically. The results show that the Nasioi have large permanent teeth like other Australoid populations whereas the deciduous teeth are only of moderate size. The coefficients of variation are large in the permanent teeth compared to other populations but the sexual dimorphism in tooth size and variability is not remarkable. Morphologically, the permanent teeth of the Nasioi are characterized by a cusp number pattern, a high frequency of the Dryopithecus + pattern on the first mandibular molar, few individuals with a Cusp of Carabelli, and a moderate expression of shovelled-shaped anterior teeth.

The functional anatomy of the lower limb of the howler monkey (Alouatta caraya).

Abstract: The howler monkey possesses unique anatomical adaptations associated with its arboreal habit. The behavioral elements are described by locomotor pattern, substrate, timing and rhythm of movement. The most significant motor adaptations are correlated clearly and directly with musculoskeletal features of the lower limb. The orientation of the joints within the limb, the shape of the joint surfaces, their bony environments, and the important planes of muscular control are the foundations for the observable locomotor behaviors.

Density of fresh and embalmed human compact and cancellous bone.

Abstract: This investigation was undertaken to determine the densities of fresh human compact and cancellous bone, with its marrow constituents intact, and compact and cancellous bone taken from embalmed cadavers. The density of 107 bone specimens was determined on the basis of the weight and volume of each specimen. Mean density results were: (1) fresh compact bone, 1.85; (2) fresh cancellous bone, 1.08; (3) embalmed compact bone, 1.85; and (4) embalmed cancellous bone, 1.09. Embalming did not appear to have altered the density of either compact or cancellous bone. It was observed also that the densities of several bone specimens taken from the same area of one bone varied greatly.

The conference on standardization of anthropometric techniques and terminology (a report)

Abstract: The conference, attended by anthropologists, engineers, dental and medical researchers, physical educationists and statisticians, took place on 28–30 March 1967 in the Aerospace Medical Research Laboratories, Wright-Patterson Air Force Base, Ohio. The ultimate purpose was to improve the comparability of anthropometric data from all workers, by establishing standards for the many new dimensions required in engineering anthropology, and by developing a terminology that reconciles the new standards with previous usages. In this effort, the group selected a list of dimensions (though with dissent on type and number) recommended as a minimum for all human biological surveys; and they chose from previous usage a terminological structure whose form, content and mode of presentation they recommended as standard practice by all anthropometrists. Both official and dissenting lists are presented, and the terminological structure is described, with examples. Despite solid progress toward a standardized technology encompassing both classical and modern practices, the conference left numerous points of technique or terminology unsettled, some of which are briefly described. Hence future meetings appear necessary, perhaps annually, until such remaining problems can be resolved.

Secular trend in height and weight within old American families at Harvard, 1870–1965. I. Within twelve four-generation families

Abstract: Among 85 members of 12 Old American families in which four generations were measured at Harvard, there were 12 fathers, 24 sons, 30 grandsons, and 19 great-grandsons. Mean birthdates for the four generations were 1858, 1888, 1918, and 1941, and mean ages when measured were 21.9, 19.0, 18.9, and 18.8 years. There was a significant increase in height between generations I and II (2.63 cm, p<0.02), a smaller rise (1.14 cm, not significant) to generation III, and no rise at all to generation IV. Weight rose negligibly until generation III and then increased 1.9 kg (not significant) to generation IV. The ponderal index, height/, rose slightly to generation III, then fell significantly (p<0.02) in generation IV to its original value in generation I. These findings confirm other indications that the secular increase in height has ended among economically-favored Americans. Weight, on the other hand, may still be increasing.

Vertebral arch defects in the lumbar vertebrae of pre-historic American Eskimos. A study of skeletons in the American Museum of Natural History, chieely from Point Hope, Alaska

Abstract: The incidence of lumbar vertebral arch defects was studied in 295 Eskimo skeletons now in the American Museum of Natural History, New York, which were obtained from adjacent burial grounds at Point Hope, Alaska. One burial ground containing 47 skeletons was used by the Ipiutak at about the start of the Christian era. The other burial ground was used by the Tigara a thousand years later and contained 248 skeletons. The lesion is a separation of the vertebral arch from the vertebral body. It usually involves the fifth lumbar vertebra but may involve others and more than one. The present incidence in the United States is about 7%. Among the Tigara the incidence was 45% and more than twice that of the Ipiutak, 21%. The youngest case was in a child of five and the deformity was uncommon before adult life. The incidence and extent of the lesion increased with age suggesting an hereditary weakness as an etiological factor. No other etiological factor could be determined although several were considered. The clinical disability could not be determined but it seemed to have no effect on longevity.

A microscopic study of the marmoset claw and nail

Abstract: W. E. Le Gros Clark concluded in his study of the problem of the primate claw that the essential difference between claw and nail is the presence of a terminal matrix associated with a deep layer in the claw, whereas neither terminal matrix nor deep layer exists in the nail. He demonstrated that the marmoset claw (which tips every digit except the hallux) has a thin deep layer and a recognizable terminal matrix. The present paper reports and discusses evidence that the marmoset nail also has a deep layer and terminal matrix. Although the importance of these structures in the claw is not disputed, it appears that these can no longer be considered absolute differences between claw and nail. On the basis of this evidence, it cannot be claimed that the presence of the deep layer and terminal matrix determines the distinctive shape of the claw as opposed to the nail.

Distribution of hereditary factors in the blood of Indians of the Gila River, Arizona.

Abstract: This paper reports the distribution of blood groups, A-B-H secretors, haptoglobins, transferrins and hemoglobin types among Indians of the Gila River Valley in Arizona. Specimens were procured from the following putative full-bloods: 909 Pima, 37 Papago, and 124 Maricopa; and from the following known mixed-bloods: Pima-Papago 134, Pima-Maricopa 26, Pima-Other Indian 41, Pima-Caucasian 33. These 1304 samples were tested for factors in the A-B-O, M-N-S-s, P, Rh-Hr, Lutheran, Kell-Cellano, Lewis, Duffy, Kidd and Diego blood group systems, and for additional blood factors (Wra), Doa, Vel, Yta, Coa, Gya, Sav, and L. W. Serum samples were tested for haptoglobins and transferrins. Hemolysates, prepared from whole blood, were tested for hemoglobin types. The results are presented on appropriate tables as number and per cent of phenotypes for the various blood group antigens and their calculated allele frequencies. Locations of the populations from which blood samples were procured are shown on a map (fig. 1). Tests made by earlier workers on the blood of Arizona Indians and related tribes are presented for comparison and discussed. The usual high frequencies for allele O reported in Amerinds was found among the putatively full-blood Gila Indians; the 124 Maricopa presented the maximum frequency of 1.000. High frequencies were reported generally for M, s, P1, R1 (CDe), R2 (cDE), k (100%) Fy, and Doa alleles. Low frequencies were reported for N, S, r (cde), R° (cDe), fy, Le1w and Dia (Pima only). There was a wide variation in frequencies for jk, and Hp1, and there were 17 Transferrin Tf B1C observed in 270 Pima samples tested. All the remaining were classified as Tf C except two Tf B;C from mixed-bloods. All samples tested for Vel, Yta, Coa, Sav, and Hemoglobin (A) showed the maximum frequency (1.000) for their genes. The following antigens were completely absent: Lua, Mia, Vw, Mta, p, Pk, ry (CdE), K, and Wra. The results of this study suggests that the Papago tribe presents fewer genes of non-Indian origin than the Pima, and the Maricopa least of the three populations.

A note on the fragmentary Sterkfontein scapula.

Abstract: Certain features of the Sterkfontein scapular fragment have been examined in the light of available data relating to the form of the scapula in primates. One suggestion currently in the literature, that this fragment is relatively less specialized than the corresponding region of the gibbon and chimpanzee (being more like some extant monkeys), may not be justified.

Growth of the human mandibular angular process: A functional cranial analysis

Abstract: The angular process of the human mandible alters its inclination with age, changing from a medial to a lateral flare during the transition from the neonatal to the adult stages. The morphological change in this mandibular skeletal unit is shown to be associated with a change in orientation of a portion of the related functional matrix, the masseter muscle. This change to an oblique line of action from an originally vertical one is associated with an increase in the functional movement of protraction at the temporo-mandibular joint. No other physiological parameters of muscle function seemingly are associated with this skeletal alteration. The processes of interaction between the functional matrix and its related skeletal are as yet unknown.

Asymmetry in East African skulls.

Abstract: Skulls from 297 East Africans were examined in relation to their symmetry; 98% were found to be asymmetrical. The most common types of asymmetry were right fronto-petalia, left parieto-petalia, and left occipito-petalia (21.2%). No significant differences were found among the East African populations. Sixteen per cent of the skulls had wormian bones, all of which were found in asymmetrical skulls. The problem of asymmetry of skulls is discussed and the literature on the subject reviewed.

The African custom of tooth mutilation in America.

Abstract: A broad historical sketch of tooth mutilation stresses the role of Negro slaves in introducing the African custom into America, and the possibility of filling in gaps in our knowledge along this line from recovered skeletal remains. As an example of what can be learned, a skeleton found recently in Grenada, West Indies, is described as that of a male Negro, with a West African type of dental mutilation. The individual represented is shown to have been around 35–40 years of age, below average in size, with bandy legs, signs of mild deficency disease, and a variety of dental and periodontal diseases. Geographical and historical factors are reviewed in an effort to decide whether or not he was one of the original slaves or a descendant of a slave. The authors conclude that the circumstances of the find warrant the belief that he had been born in Africa and received his mutilation there. An earlier report of another such find in Barbados, and the mention of a subsequent find in St. Croix, suggest that a more intensive search for Negro remains in the West Indies would prove fruitful.

Growth of bones as revealed by implant markers in animals.

Abstract: Implantation of screws, pegs, wires, or other material as markers has been of value during the last 200 years in the serial study of growth of bones. With this direct method, for a given period, the increase in distance between implants on either side of an endochondral growth center or suture can be readily determined. In contrast, the relatively constant position of two or more implants within a single bone can be utilized to establish the pattern of peripheral apposition and resorption. When radiopaque implants are used in combination with serial roentgenography, not only the amount but also the rate, periods of activity and relative direction of growth may be determined. This indirect method obviates reoperating or killing the animal to measure the distance between implants. Some of the problems in the use of these methods are that (1) growth occurs in more than one plane, (2) the implants may not remain where inserted into the bone, (3) the implants may not be in a plane parallel to the X-ray film, and (4) the distance between the implants and the film may not be constant. (Abstract previously published Am. J. Phys. Anthrop., 27: 236, September, 1967).

Normal craniofacial skeletal growth of the rat.

Abstract: Growth of the craniofacial structures in the rat was studied with a vital-staining technique. The study was designed to determine the amount and direction of growth in the midsagittal region. A group of 44 male Long Evans rats weighing 90 gm ± 5 gm were given intraperitoneal injections of bone-marking agents. These injections consisted of terramycin, alizarin red S, trypan blue, and terramycin, plus alizarin red S, at 0, 3, 15 and 36 days after attainment of the standard starting weight. Cephalometric radiographs were made at the time of each injection. The rats were sacrificed at 66 days. Serial undecalcified sections were cut in the midsagittal plane at 80 μ. Certain anatomical landmarks were located on each section, coordinated, and plotted; a calibrated microscope stage and graduated eyepice were used. Specific areas of interest were photographed in color, with single-frame exposures, on 16 mm moving film. The specific growth sites were then analyzed on a Vanguard Motion Analyzer by measuring the separation of the individual bone marks.

Procion dyes as matrix markers in growing bone and teeth.

Abstract: Twelve mono- and dichloro-s-triazinyl dyes were selected to ascertain the vital-staining characteristics of these dyes, to evaluate the toxicity, and to establish an optimal rate of doseage for use with several animal species. In addition to these dyes (also known in the dye industry as Procion compounds), tetracycline hydrochloride and a hematoporphyrin derivative were also studied. the experimental animals used were mice, rats, rabbits, cats, dogs, and monkeys. The agents were given in a single dose or multiple doses at selected time intervals, after which the experimental animals were sacrificed and the tissue removed for examination. The tissues were examined grossly and with various microscopic methods, and after being placed in clearing solutions for various time periods. The dyes selectively stained bone, dentin, and cementum, which were being formed at the time of administration. Certain dyes have marked advantages over others, not only in staining characteristics but also in toxicity and fluorescence.

Tetracycline bone labeling in anatomy

Abstract: Tetracyclines are deposited in vivo at centers of active bone formation, and can be seen by fluorescence microscopic examination of undecalcified bone sections. With this marker, the rate of bone formation at the level of the osteon can be measured, and is taken to indicate the speed of bone formation at the level of the osteoblast. When the number of bone-forming centers is then counted, it becomes possible to compute: (1) the number of new centers initiated per unit time, which number is taken to indicate the number of new osteoblasts created from the osteoprogenitor cell (mesenchymal cell) pool; (2) the rate of bone formation averaged over the whole sample, which is the form of protein anabolism characteristic of bone. Therefore the tetracycline-labeling technique permits the quantitative analysis of skeletal growth, as well as the maintenance of the mature skeleton, in terms of tissue dynamics and cell population dynamics. Of major importance in the design of future studies is the frequent finding that abnormalities in the rate of bone formation over the whole tissue may be the opposite of abnormalities in the rate of bone formation at the level of the osteoblast. This situation can exist because osteoprogenitor cell behavior can – and frequently does – produce major changes in the total number of functional osteoblasts, changes which do not correlate with changes in the behavior of individual osteoblasts.

A note on the Olduvai clavicular fragment.

Abstract: Certain features of the Olduvai clavicular fragment have been examined in the light of data already existing on the form of the clavicle in primates. Although similar to that of modern man, the fragment exhibits features which suggest that its function may have differed somewhat from that of the clavicle in man. The new information correlates well with that obtained from the fragmentary Sterkfontein scapula.

Chloro-s-triazines as markers and fixatives for the study of growth in teeth and bones.

Abstract: Cyanuric chloride (2,4,6-trichloro-s-triazine) and dichloro-s-triazinyl Procion M (Imperial Chemical) dyes and colorless compounds covalently bond or covalently cross-link with H-active functional groups in tissues including enamel, dentin, and bone. By cross-linking, chloro-s-triazines make irreversibly insoluble in situ various exogenous or endogenous components, which are lost or artifactually diffused by other methods of fixation. Cyanuric chloride (0.5%) and N-methyl morpholine (1%) in anhydrous methanol provide an excellent cytologic fixative, with N-methyl morpholine or other suitable tertiary amines serving as “quaternizing” catalysts and HCl acceptors. Highly permeable Procion M dyes were used topically as freshly prepared 5–10% aqueous solutions; 2% solutions in 5% dextrose were also given intravenously at a dosage level of 200 mgm/Kgm. Since topically applied dyes stain irreversibly, they can be employed as markers for the study of various pathophysiologic processes associated with the tooth and periodontal apparatus; that is, for the study of growth and development. Given intravenously, these dyes permanently mark incremental lines and zones of growth in tooth and bone; the markers persist during processing and decalcification of the specimens. Vinyl-sulfonyl Remazol (American Hoechst) and other, classes of reactive dyes were also used as permanent markers.

Experimental cold modification of cranio-facial morphology.

Abstract: A possible relationship between cranio-facial form and growth under cold stress was investigated through a control group (N=17)—experimental group (N=14) comparison. Two groups of young rats were exposed to 90 days of 22°C and 5°C temperatures respectively. Methods of analysis included measurement of overall bodily dimensions as well as detailed examination of the cleaned, dried skulls and femora. Statistical comparison of the cold and non-cold grown rats showed a number of highly significant mean differences; particularly a narrower nose, rounder neurocranium, and shorter femur was seen in the cold stressed animals. Human anatomical homologs were briefly noted as were their possible genetic and ontogenetic causes.

Further evidence for continuing bone expansion

Abstract: Additional and extended data on 2726 subjects from Costa Rica, Honduras, Nicaragua and Panama provide confirming evidence for continuing bone expansion of the second metacarpal at midshaft. As shown in 4924 subjects from eight populations, subperiosteal apposition is more rapid in the female than in the male, and accounts for a net increase of 10% in cross-sectional area from age 25 to age 85. Unlike endosteal resorption, which is precipitous in onset, adult subperiosteal gain is continuous from the third through the ninth decades.

Associations between discontinuous cranial traits.

Abstract: The associations of discontinuous variants (accessory ossicles, parietal foramina, and fronto-temporal articulation) at seven circumparietal sites were tested by deriving chi-squares and contingency coefficients for each pair of sites in 366 crania (N=732 sides) of the Morton collection, divided into six geographic racial subsamples. Seventy-four of 85 race specific coefficients were positive and 25 of these were significant at the 0.05 level, while 11 of the 15 total sample coefficients were significant at the 0.01 level. Considerable racial variation was exhibited in the number and pattern of associations. Associations between adjacent sites were higher than those between non-adjacent sites. This neighborhood pattern of associations is discussed with reference to a model in which many of the factors which produce these discontinuous variants operate on a regional scope, encompassing several neighboring sites, with overlapping of the regions affected by different factors.

The occurrence of the septal perforation of the humerus in three non-human primate species.

Abstract: Evidence is presented concerning the occurrence of the coronoid-olecranon perforation of the humerus in three species of Old World monkeys. Significant relationships are found to exist between the occurrence of the perforation and smaller minimum midshaft diameters of humeri, younger ages, and more protruding processes of ulnae. A possible explanation for perforated coronoid-olecranon septums is advanced. The olecranon process of the ulna is found to project relatively more from the shaft in young individuals than old individuals. Since the protrusion of this process is positively correlated with the occurrence of the septal perforation, it is suggested that the articulation of the point of the ulna causes resorption of the coronoid-olecranon septum. With advancing age, the contact is broken, and the perforation is filled in. Since significant correlations are shown for the occurrence of the perforation and the size of the humerus, even for an adult sample, it seems probable that the robustness of the humerus is an inhibiting factor in the occurrence and maintenance of the perforation. In larger humeri, it is possible that the point of the ulna cannot cause complete resorption, and resorption would be more likely to cause a perforation in humeri with thinner coronoid-olecranon septums. Because extreme extension of the elbow always forms an angle considerably less than 180° between the axes of the shafts in the humerus and the ulna in these monkeys, it is strongly indicated that hyperextension of the elbow joint beyond 180° is not a primary cause of the septal perforation when it appears in man.

Natural markers in bone growth.

Abstract: Three features in the long bones, shown by radiograms, have been used as markers for the study of bone growth. (I) Transverse lines of arrested growth. Radiograms of six long limb bones from 1,576 individuals were investigated for clearness and persistence of these lines. Both ends of tibia and fibula showed very high frequency of suitable lines for markers, possibly also the distal end of femur and radius. (II) Notches in the base of second and fifth metacarpal bones. Measurements of growth from apex of the basal notch to the ends of the shaft were performed on serial hand radiograms. The proportion of growth from distal and basal ends averaged 87:13 in the second and 80:20 in the fifth metacarpal bones. (III) Nutrient canals. The initial point of ossification was determined by a prolongation of the nutrient canal intersecting the central axis of the medullary cavity. The proportion of growth from that point to distal and basal ends of the shaft averaged 68:32 and 64:36 for the second and the fifth metacarpal bones, respectively. These values are significantly different from the measurements obtained from the notches.

Distribution of hereditary blood groups among Indians in South America. V. In northern Brazil.

Abstract: This paper reports the results of tests made for hereditary antigens in blood samples procured from Indians in northern Brazil. Specimens were procured from 423 putatively full-blood persons of the following tribes: in the province of Roraima from 261 Macuxi, 48 Uaica, 27 Xirixano, 10 Uapixana, 9 Cacarapai and 9 Paramiteri; in Para from 21 Assurini; and in Amapa from 38 Galibi. Erythrocyte samples were tested for factors in the A-B-O, M-N-S-s, P, Rh-Hr, Lutheran, Kell-Cellano, Lewis, Duffy, Kidd and Diego systems. Serum samples were tested for haptoglobins and transferrins. Hemolysates, prepared from whole blood, were tested for hemoglobin types. The results are presented on appropriate tables as number and per cent of phenotypes for the various blood group anigens and their calculated gene frequencies. Locations from which blood samples were procured are listed in the tables and shown on a map (fig. 1). All the 423 samples except one Macuxi belonged to group O. The Uaica tribe had a low frequency for M (0.534). All others showed the high frequency usually observed in Amerinds. The s allele was high in all except the Galibi in which the frequency was (0.500). Frequencies for P2 was higher than for P1 in all except the Assurini and Galibi, theirs was high for P1 (1.00) and low for P2 (0.00). The frequencies for R1 (CDe) and R2 (cDE) were high and all others in the Rh-Hr system were low or absent. All specimens were positive for Cellano (k) and negative for Kell (K). There was a complete absence of Lewis (Le1), excepting in the Uaica and Xirixano in which populations Fya allele frequencies were higher than 0.500. The distribution of the Jk (a+) phenotype and corresponding ellele frequencies varied widely in Brazilian Indians as did those for Diego (a+). The haptoglobin Hp1 allele frequencies were in essential agreement with those reported elsewhere for Indians in South America, and all transferrins determined were classified as Tf C. All samples tested for homoglobin types contained homoglobin (A) as a major component, but five members of the Galibi tribe possessed hemoglobin (S) as well.

The secular trend in the diameter of the femur of American Whites and Negroes

Abstract: The transverse diameter of the adult femur at the level of its mid-bicondylar length is related to length, age and year of birth in American White and Negro skeletons of both sexes of the Terry Collection. The coefficients of correlation between age at death and birth year are significant in all four sex-race groups, as are also the regression coefficients of transverse diameter on length and on age. The regression of length on age is negative and on birth year positive, although statistically significant only in the Negro male group. The partial regression coefficients of transverse diameter on length, on age, and on birth year, each eliminating the effects of the other two variables, are significant for length, not significant for age except in the Negro male group, and significant for birth year except in the Negro male group. Thus, the statistics of three of the sex-race groups do not support the hypothesis that transverse diameter of the femur increases with age, but rather suggest a negative secular trend; the apparent inconsistency in these findings of the Negro male group can, however, be considered insignificant from a statistical point of view.

The skin of primates. XXXVI. The skin of the pigmy marmoset — Callithrix (=Cebuella) Pygmaea†

Abstract: The pigmy marmoset — Callithrix (= Cebuella) pygmaea Spix — is the second detailed study of the members of the family Callithricidae. It is closely allied to the red-mantled tamarin — Saguinus (=Tamarinus) fuscicollis illigeri Spix — and shares some of its characteristics with both Prosimii and Anthropoidea. The epidermis and dermis contain moderate numbers of concurrent, melanotic melanocytes. The dermis is rich in elastin. Hair follicles grow in groups of three or four over the general body surface, and one apocrine gland is associated with each grouping. Arrectores pilorum muscles are well developed. On the ventral ulnar wrist are sinus hairs associated with apocrine glands. Most hair follicles have nerve end-organs around them that are reactive for acetylcholinesterase and alkaline phosphatase. There is a large aggregation of sebaceous glands in the suprapubic region. The large sebaceous glands in the eyelid, face, and external genitalia are surrounded by cholinesterasereactive nerves. Apocrine glands are found over most of the hairy skin except the brow, scalp and back; a large grouping of them is present in the sternal region. Only the secretory coils of apocrine glands in the external genitalia are invested with butyrylcholinesterase-rich nerves. Eccrine glands are confined to the volar surfaces of the pes and manus. They have dark cells with abundant glycogen and clear cells with neither glycogen nor PAS-reactive material. The nerves around the eccrine secretory coil are reactive only for acetylcholinesterase.