So far as cerebral structure goes, therefore, it is clear that man
differs less from the chimpanzee or the orang, than these do even from
the monkeys, and that the difference between the brain of the
chimpanzee and of man is almost insignificant when compared with that
between the 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
successively 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
gorilla, and so on of a Hylobates, Semnopithecus, Cynocephalus,
Cercopithecus, Macacus, 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 to p. 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
knowledge 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 its 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
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