202 The Descent of Man. Part 1 



" differs less from the chimpanzee or the orang, than these do even 

 "from the monkeys, and that the difference between the brain of the 

 u chimpanzee and cf man is almost insignificant, when compared with, 

 " that between tbe chimpanzee brain and that of a Lemur." 



In the paper to which I have referred, Professor Bischoff does not 

 deny the second part of this statement, but he first makes the irrelevant 

 remark that it is not wonderful if the brains of an orang and a Lemur 

 are very different ; and secondly, goes on to assert that, " If we sueces- 

 4 * sively compare the brain of a man with that of an orang ; the brain of 

 ** this with that of a chimpanzee ; of this with that of a yorilla, and so 

 "on of a Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus. 

 u Cebus, Callithrix, Lemur, Stenops, Hapale, we shall not meet with a 

 " greater, or even as great a, break in the degree of development of the 

 "convolutions, as we find between the brain of a man and that of an 

 " orang or chimpanzee." 



To which I reply, firstly, that whether this assertion be true 

 or false, it has nothing whatever to do with the proposition enunciated 

 in 'Man's Place in Nature,' which refers not to the development of the 

 convolutions alone, but to the structure of the whole brain. If Professor 

 Bischoff had taken the trouble to refer top. 96 of the work he criticises, 

 in fact, he would have found the following passage: "And it is a 

 " remarkable circumstance that though, so far as our present know- 

 " ledge extends, there is one true structural break in the series of forms 

 " of Simian brains, this hiatus does not lie between man and the 

 " manlike apes, but between the lower and the lowest Simians, or in 

 "other words, between the Old and New World apes and monkeys and 

 "the Lemurs. Every Lemur which has yet been examined, in fact, 

 " has its cerebellum partially visible from above ; and its posterior lobe, 

 " with the contained posterior cornu and hippocampus minor, more or 

 "less rudimentary. Every marmoset, American monkey, Old World 

 " monkey, baboon, or manlike ape, on the contrary, has ii3 cerebellum 

 " entirely hidden, posteriorly, by the cerebral lobes, and possesses a 

 "large posterior cornu with a well-developed hippocampus minor." 



This statement was a strictly accurate account of what was known 

 when it was made; and it does not appear to me to be more than 

 apparently weakened by the subsequent discovery of the relatively 

 small development of the posterior lobes in the Siamang and in the 

 Howling monkey. Notwithstanding the exceptional brevity of the 

 posterior lobes in these two species, no one will pretend that their 

 brains, in the slightest degree, approach those of the Lemurs. And 

 if, instead of putting Hapale out of its natural place, as Professor 

 Bischotf most unaccountably does, we write the series of animals 

 he has chosen to mention as follows : Homo, Pithecus, Troglodytes, 

 Hylobates, Semnopithecus, Cynocephalus, Cereopithecus, Macacus, Cebus, 

 Callithrix, Hapale, Lemur, Steiuqjs, I venture to reaffirm that the 

 great break in this series lies between Hapale and Lemur, and that 

 tiiis break is consideiably greater than that between any other two 

 terms of that series. Professor Bischotf ignores the fact that long 

 before ho wrote, Gratiolet had suggested the separation of the Lemurs 

 from the other Primates on the very ground of the difference in their 

 cerebral characters ; and that Professor Flower had made the following 

 ooservations in the course of his description of the brain of the Javan 

 Loris." 



7S 



' Transactions of the Zoological Society,' vol. \ 1862. 



