This important Huxleian law, the chief consequence of which is "the descent of man from the ape," has lately been confirmed in an interesting and unexpected way from the side of the experimental physiology of the blood. The experiments of Hans Friedenthal at Berlin have shown that human blood, mixed with the blood of lower apes, has a poisonous effect on the latter; the serum of the one destroys the blood-cells of the other. But this does not happen when human blood is mixed with that of the anthropoid ape. As we know from many other experiments that the mixture of two different kinds of blood is only possible without injury in the case of two closely related animals of the same family, we have another proof of the close blood-relationship, in the literal sense of the word, of man and the anthropoid ape.
(FIGURE 1.203. Lar or white-handed gibbon (Hylobates lar or albimanus), from the Indian mainland (From Brehm.)
FIGURE 1.204. Young orang (Satyrus orang), asleep.)
The existing anthropoid apes are only a small remnant of a large family of eastern apes (or Catarrhinae), from which man was evolved about the end of the Tertiary period. They fall into two geographical groups—the Asiatic and the African anthropoids. In each group we can distinguish two genera. The oldest of these four genera is the gibbon Hylobates, Figure 1.203); there are from eight to twelve species of it in the East Indies. I made observations of four of them during my voyage in the East Indies (1901), and had a specimen of the ash-grey gibbon (Hylobates leuciscus) living for several months in the garden of my house in Java. I have described the interesting habits of this ape (regarded by the Malays as the wild descendant of men who had lost their way) in my Malayischen Reisebriefen (chapter 11). Psychologically, he showed a good deal of resemblance to the children of my Malay hosts, with whom he played and formed a very close friendship.
(FIGURE 1.205. Wild orang (Dyssatyrus auritius). (From R. Fick and
Leutemann.))
The second, larger and stronger, genus of Asiatic anthropoid ape is the orang (Satyrus); he is now found only in the islands of Borneo and Sumatra. Selenka, who has published a very thorough Study of the Development and Cranial Structure of the Anthropoid Apes (1899), distinguishes ten races of the orang, which may, however, also be regarded as "local varieties or species." They fall into two sub-genera or genera: one group, Dissatyrus (orang-bentang, Figure 1.205), is distinguished for the strength of its limbs, and the formation of very peculiar and salient cheek-pads in the elderly male; these are wanting in the other group, the ordinary orang-outang (Eusatyrus).
(FIGURE 1.206. 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
Figure 1.207) in the structure of the head, the colouring, and the
absence of hair in parts.)
Several species have lately been distinguished in the two genera of the black African anthropoid apes (chimpanzee and gorilla). In the genus Anthropithecus (or Anthropopithecus, formerly Troglodytes), the bald-headed chimpanzee, A. calvus (Figure 1.206), and the gorilla-like A. mafuca differ very strikingly from the ordinary Anthropithecus niger (Figure 1.207), not only in the size and proportion of many parts of the body, but also in the peculiar shape of the head, especially the ears and lips, and in the hair and colour. The controversy that still continues as to whether these different forms of chimpanzee and orang are "merely local varieties" or "true species" is an idle one; as in all such disputes of classifiers there is an utter absence of clear ideas as to what a species really is.
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 Figure 1.208), not only by its unusual size and strength, but also by a special formation of the skull. This giant gorilla (Gorilla gigas, Figure 1.209) 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.
(FIGURE 1.207. Female chimpanzee (Anthropithecus niger). (From Brehm.)