L'hap. VII. Structure of the Brain. 205 



view that man has been evolved from some ape- like form ; though thero 

 can be no doubt that that form was, in many respects, different from 

 any member of the Primates now living. 



Von Baer taught us, half a century ago, that, in the course of theit 

 development, allied animals put on, al first, the characters of the greater 

 groups to which they belong, and, by degrees, assume those which restrict 

 them within the limits of their family, genus, and species ; and he 

 proved, at the same time, that no developmental stage of a higher 

 animal is precisely similar to the adult condition of any lower animal. 

 It is quite correct to say that a frog passes through the condition of a 

 fish, inasmuch as at one period of its life the tadpole has all the cha- 

 racters of a fish, and, if it went no further, would have to be grouped 

 among fishes. But it is equally true that a tadpole is very different 

 from any known fish. 



In like manner, the brain of a human foetus, at the fifth month, may 

 correctly be said to be, not only the braiu of an ape, but that of an 

 Arctopithecine or marmoset-like ape ; for its hemispheres, with their 

 great posterior lobster, and with no sulci but the sylvian and tho 

 calcarine, present the characteristics found only in the group of tho 

 Arctopithecine Primates. But it is equally true, as Gratiolet remarks, 

 that, in its widely open sylvian fissure, it differs from the brain of any 

 actual marmoset. No doubt it would be much more similar to the brain 

 of an advanced foetus of a marmoset. But we know nothing whatever 

 of the development of the brain in the marmosets. In the Platyrhini 

 proper, the only observation with which I am acquainted is due to 

 Pansch, who found in the brain of a foetal Cebus Apella, in addition to 

 the sylvian fissure and the deep calcarine fissure, only a very shallow 

 anterotemporal fissure (soissure parallele of Gratiolet.) 



Now this fact, taken together with the circumstance that the antoro- 

 temporal sulcus is present in such Platyrhini as the Saimiri, which 

 present mere traces of sulci on the anterior half of the exterior of the 

 cerebral hemispheres, or none at all, undoubtedly, so far as it goes, 

 affords fair evidence in favour of Gratiolet's hypothesis, that the 

 posterior sulci appear before the anterior, in the brains of the 

 Platyrhini. But, it by no means follows, that the rule which may hold 

 good for the Platyrhini extends to the Catarhini. We have no in- 

 formation whatever respecting the development of the brain in the 

 Cyaomorpha : and, as regards the Anthropomnrpha, nothing but the 

 account of the brain of the Gibbon, near birth, already referred to. 

 At the present moment, there is not a shadow of evidence to shew 

 that the sulci of a chimpanzee's, or orang's, brain do not appear in the 

 same order as a man's. 



Gratiolet opens his preface with the aphorism. " II est dangereux 

 " dans les sciences de conclure trop vite." I fear he must have for- 

 gotten this sound maxim by the time he had reached the discussion of 

 the differences between men and apes, in the body of his work. No 

 doubt, the excellent author of one of the most remarkable contributions 

 to the just understanding of the mammalian brain which has ever been 

 made, would have been the first to admit the insufficiency of his data 

 had he lived to profit by the advance of inquiry. The misfortune ia 

 that his conclusions have been employed by persons incompetent to 

 appreciate their foundation, as arguments in favour of obscurantism. 80 



80 For example, M. l'Abbe Lecomte winisme et Torigine de l'Homme 

 in his terrible pamphlet 'Le Dar- 1873. 



