462 LECTURE XVI. 



species ; that, therefore, we are justified in assuming diflPerent 

 species in mankind, just as in several domestic animals' of high 

 antiquity. I touched upon the antiquity of mankind, and pointed 

 out the differences in the human species, which, at the beginning 

 of the stone-period, inhabited the earth. We then glanced at 

 the origin of new races and species, and arrived at the conclusion, 

 that transformation, adaptation, natural selection, are processes 

 in nature explanatory of the various forms of which the organic 

 world consists. We may, therefore, now proceed to discuss the 

 last question, — namely, whether the theory of the derivation of 

 the human type from the simian group is scientifically admissible. 

 The existing materials for bridging over the gulf between 

 man and ape I have placed before you. I have shown in what 

 points the three anthropoid apes estabhsh the similarity ; in 

 what respects the races of mankind, and especially the Negro, 

 approach the ape-type, without, however, completely reaching 

 it. I have demonstrated that the oldest cave-skulls known 

 to us decidedly approach the ape-type, both by the elongated 

 form and the low arching of the skull. I have, finally, di- 

 rected your attention to the microcephali, those congenital idiots, 

 not as constituting a separate species, as some of my detractors 

 make me say, but as a morbid arrest of development, which 

 indicates one of the stages which the human embryo must ne- 

 cessarily pass through, and which now in its abnormity repre- 

 sents that intermediate form, which at a remote period may 

 have been normal. I remind you on this occasion of what I 

 said concerning these microcephaH, together with Gaudry^s 

 remark on the Greek monkey. Just as Gaudry observed that 

 the whole skull of the Greek monkey would constitute it a 

 Semnopithecus had not the hmbs been found, which present 

 the type of the macacus, so, I remarked, might the skull of a 

 microcephalus, found in a fossil state, in the absence of the 

 jaws be mistaken for that of an ape, until the discovery of the 

 limbs should establish the human type. But as it is certain 

 that the microcephalus, with his arrested development, is not 

 suited for propagation, it is neither the only possible nor the 

 only imaginable intermediate form between man and ape. But 

 this arrest which the brain experienced in its forward march, 

 is the simian stage. This abnormal creature, this arrested 



