Fig. 206—The bald-headed chimpanzee (Anthropithecus calvus). Female. This fresh species, described by Frank Beddard in 1897 as Troglodytes calvus, differs considerably from the ordinary A. niger Fig. 207) in the structure of the head, the colouring, and the absence of hair in parts.
Of the largest and most famous of all the anthropoid apes, the gorilla, Paschen has lately discovered a giant-form in the interior of the Cameroons, which seems to differ from the ordinary species (Gorilla gina Fig. 208), not only by its unusual size and strength, but also by a special formation of the skull. This giant gorilla (Gorilla gigas, Fig. 209) is six feet eight inches long; the span of its great arms is about nine feet; its powerful chest is twice as broad as that of a strong man.
Fig. 207—Female chimpanzee (Anthropithecus niger). (From Brehm.)
The whole structure of this huge anthropoid ape is not merely very similar to that of man, but it is substantially the same. “The same 200 bones, arranged in the same way, form our internal skeleton; the same 300 muscles effect our movements; the same hair covers our skin; the same groups of ganglionic cells compose the ingenious mechanism of our brain; the same four-chambered heart is the central pump of our circulation.” The really existing differences in the shape and size of the various parts are explained by differences in their growth, due to adaptation to different habits of life and unequal use of the various organs. This of itself proves morphologically the descent of man from the ape. We will return to the point in Chapter XXIII. But I wanted to point already to this important solution of “the question of questions,” because that agreement in the formation of the embryonic membranes and in fœtal circulation which I have described affords a particularly weighty proof of it. It is the more instructive as even cenogenetic structures may in certain circumstances have a high phylogenetic value. In conjunction with the other facts, it affords a striking confirmation of our biogenetic law.
Fig. 208—Female gorilla. (From Brehm).