Volume 1
On the anatomy, physiology, and pathology of the chimpanzee / by Charles F. Sonntag.
- Sonntag, Charles F. (Charles Frederick), -1925
- Date:
- 1923
Licence: In copyright
Credit: On the anatomy, physiology, and pathology of the chimpanzee / by Charles F. Sonntag. Source: Wellcome Collection.
100/118 page 420
![The suppressive agents are the various ductless glands. When they are diseased the suppressive power is removed, the latent power reasserts itself, and Man assumes certain ape-like characters. Man, in fact, retains more foetal characters than the Chimpanzee. The most distinctive character of the human foetus is the foot, for it has never been seen with the hallux projecting from the postero-mesial aspect of the sole. The Chimpanzee differs from the white races of Man in its pigmented, hairy skin, its thick lips, and its overgrown facial skeleton, which exhibits large supra-orbital crests, prominent zygomata and malar bones, prognathism and large mandible. But diseases of the ductless glands cause Man to assume one or more of these characters, for they remove the suppressive agencies. In Addison’s disease of the supra-renal capsules the skin becomes pigmented; and in the various disorders of the pituitary body, so beautifully monographed by Cushing (15), the lips thicken, the skull exhibits large crests, zygomata and malar bones, maxillary or mandibular prognathism occurs, and there is a variable amount of hirsuties. The extremities also become large and clumsy. Many of these conditions are present as the normal characteristics in the lower races of Man ; and one of the most prominent features in the skull of Homo rhodesiensis is the enormous development of the supra-orbital crests. At a certain stage in development the foetuses of all Primates have external genital folds. In the human foetus they continue to develop and form the labia majora and mons veneris, and they bury the labia minora and clitoris. In the lower Primates they disappear and the clitoris is exposed on the surface. But the Chimpanzee exhibits an intermediate condition. The mons veneris is slight, and the labia majora are represented by two slight elevations of the skin over thickenings of the subcutaneous tissue (PI. I. fig. C). The chief difference between the Chim- panzee and Man is the absence of the hymen. In diseases of the ductless glands the organs atrophy in Man. The biochemical reactions of the blood show that Man is related to the Chimpanzee and other Anthropoids, and it is evident from the above that the actions of the ductless glands have altered the appearances of these relatives in a pronounced manner. Bolk (7) has shown that the suppressive action has not only influenced the somatic features of Man, but it has retarded his development and succeeding life phases. He believes that the ancestor of Man changed his diet from frugivorous to omnivorous, and the change may have been the factor which evoked the suppressive action of the endocrine organs. The compressed head appears sunk between the shoulders, for the neck is short. It is also more rigid than in Man. This arrangement throws no obstacle in the way of the long arms, and the shortness of the neck may be designed to give the powerful levator anguli scapulae and levator claviculae a very strong fixed origin. [98]](https://iiif.wellcomecollection.org/image/b2982123x_0001_0100.jp2/full/800%2C/0/default.jpg)
