Variation of body color was investigated quantitatively among Japanese macaques (Macaca fuscata) and compared with other species of the genus Macaca, using a digital color meter. Color is expressed by three values: lightness, red-green, and yellow-blue. The most prominent variation of body color in Japanese macaques is well defined by geography, and the lightness correlates well with the winter temperature. However, the geographical body color cline can be also explained as cryptic function. On the other hand, groups of the Japanese macaques living in peripheral parts of Japan tend to show the varied body color. This pattern of appearance is similar to those of other morphological characters, such as skull, and it may be related to the genetic drift. The hypothesis that the cryptic coloring is the primary function for the body color in macaques, is supported also by the analysis of body color of other species of macaques, taking ecological settings of their living places into consideration.

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Anatomy of the intrinsic and extrinsic hand muscles concerning the thumb movement were studied in 6 primate species including tree shrews, slow lorises, a squirrel monkey, crab-eating monkeys, an orangutan and man. Four thenar muscles which represent the intrinsic muscles are found in all the species examined except for the tree shrews which lack M. opponens pollicis. This muscle effects an opposable movement of the thumb against the other fingers in the prosimians and the higher primates. The opposable movement which enables grasping of tools is most effective in the man. Among the four extrinsic muscles, M. extensor pollicis brevis (EPB) and M. flexor pollicis longus (FPL) are unique in the man. In the other species examined, the former is totally absent and the latter may be represented by a tendon coming from M. flexor digitorum profundus. EPB and FPL work together to flex specifically the phalangeal joint of the thumb without bending the other joints. Thereby FPL flexes the distal phalanx and the EPB stabilizes the proximal phalanx. In the other primates, flexion of the joint is inevitably accompanied by bending of the distal phalangeal joints of the other fingers, as seen in the human toes.

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Japanese monkeys with “white hands” were frequently noticed in several regions including Takasakiyama. The results of 11 years (from 1977 to 1987) observation about “white hands ”in three troops (A, B and C) of Takasakiyama are characterized as below.
1) White areas were dominantly found in forelimbs and the size of the white areas varied among monkeys from a tiny point to whole limb pads of two or three limbs. The difference between left and right was not remarkable.
2) The frequency of white hands were significantly lower in the A troop (.0291) than in the other two troops (.0667 and .0581).
3) The annual fluctuation in the occurrence rate of the white hand was significant.
4) Familial accumulation was observed at the B troops in sibs. of white hands and at the A troop in offspring from white hand mothers.
5) The phenotypic relationships were not highly correlated between mothers and offspring. The occurrence of white handed offsprings was not affected by the phenotypes of mothers.
6) The causes for limb malformation and white hand are clearly different from each other.
These results suggested the white hand is inherited character. Segregation ratios fit autosomal reccesive (possibly with incomplete penetrance) and polygenic inheritance hypotheses. No father, however, could be identified in this study, so the possibility that the white hand is controlled genetically should be tested by using offspring with identified father.

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Hair characteristics of Japanese monkeys were investigated and geographical variations of them were recognized. Namely, the Japanese monkeys inhaviting in the high latitude areas or in the cold climate tend to have relatively short hair with medium density, and those inhaviting in the warm and rainy climate tend to have long hair with low density. Because these geographical variations are closely related to the climate where the Japanese monkeys are inhaviting, it is concluded that the hair characteristics are one of the adaptive forms to the varied complicated weathers in Japan. On the other hand, to compare with other macaques, the Japanese monkeys have higher density of hair than the other macaques. Hair with high density seen in the Japanese monkeys is considered to be suitable to the cold climate in Japan located in the highest latitude as the habitats for nonhuman primates.

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External features, nerve supply and intramuscular distribution of nerves were examined in the soleus muscle in the following anthropoid apes, gorilla, orang-utan and gibbon. The muscle was solely supplied by a branch from the tibial nerve, which arose with the nerve to the lateral head of the gastrocnemius muscle and was considered to be identical with the Ramus posterior in the human soleus. In gorilla this nerve ramified within the muscle in basically the same branching pattern as in man, but in orang-utan and gibbon the intramuscular distribution patterns of the nerve were different from that in man. In gorilla the muscle was strongly attached to the popliteal line of the tibia by forming an aponeurosis, from which some muscle fascicles arose. This part of the muscle was supplied by twigs from a branch identical with the P-4 branch from the R. posterior in man. These findings suggest that the soleus with the tibial origin in gorilla represents the primitive stage of the human soleus.

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Twenty three nonmetric traits of 248 Japanese monkey skulls from 5 regions were investigated, and 22 traits showed significant geographic variation in frequency.
Fifteen traits were compared between two populations which originated in the same lowland area of Yakushima, but developed in different environments: the wild population of Yakushima and the second and third generations of the provisioned troop in Ohirayama Park, where the climate is much colder. Twelve traits did not differ in frequency between the two populations. This stability of these nonmetric traits despite environmental change suggests their high heritability.

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Detailed dissections were performed on some primates and adult cadavers to provide more accurate morphological data on the composition of the pelvic diaphragm, pudendal plexus and sacral autonomic nerves.
1) The pelvic diaphragm is generally divided into 2 parts, the ventral iliopubococcygeus (levator ani: man) and the dorsal ischiococcygeus (coccygeus: man). This laminate arrangement is distinct in macaque monkeys. In man it becomes obscure and 2 parts are blended into one sheet. Some fibers of the pubococcygeus become attached to the rectal wall and form the levator ani. This attachment has been observed in chimpanzees and gibbons. 2) The pudendal plexus is divided into 2 parts, medial and lateral at their origin. From the 2 parts, 3 nerves originate respectively. In primates as in man a laminate arrangement exists among the 3 nerves from the medial: The pelvic splanchnic nerves (PSN) are situated ventrally, the nerve to the ischiococcygeus dorsally, the nerve to the iliopubococcygeus in between. The same laminate arrangement exists among the 3 nerves from the lateral: The dorsal nerve of the penis (or clitoris) is situated ventrally, the inferior rectal nerve dorsally, the perineal nerve in between. In the macaque monkey, no obvious laminate arrangement exists and in the gibbon and chimpanzee tends to be more distinct, but is not as obvious as in man. 3) Sacral autonomic nerves are composed of PSN (parasympathetic) and sacral splanchnic nerves (SSN) (sympathetic). PSN exist always in man and primates. But, SSN are observed in 21 out of 60 pelvic halves (35.0%) in man, and none are observed in primates with the only exception of chimpanzees. SSN in primates can be considered part of PSN, and in man they have developed to become independent nerves.

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