80 ORIGINAL ARTICLES. 



2. In the anthropoid apes the cerebrum is smaller, relatively to the 

 cerebellum, than in man. 



3. In the anthropoid apes the sulci and gyri are generally less com- 

 plex, and those of the two cerebral hemispheres are more symmetrical, 

 than in man. 



4. The hemispheres are more rounded and deeper in man than in the 

 anthropoid apes, and the proportions of the lobes to one another are dif- 

 ferent. Furthermore, certain minor gyri and fissures, present in the one, 

 are absent or rudimentary in the other. 



The evidence of the first of these differences has, I believe, been uni- 

 versally admitted since the time of Soemmering. The second and fourth 

 clearly result from the observations of Schroeder van der Kolk and 

 Vrolik, and those of Gratiolet (Mem. sur les plis cerebraux des Primates, 

 1854), as will appear from the following extracts. The first citation is 

 taken from the work of the first-named authors, which seems to be so 

 little known in this country, that I make no apology for length of the 

 extract : — 



" According to very precise investigations which the first named of us has carried 

 out with reference to this point, the difference between the brains of the higher apes and 

 that of man is to be sought, not only in the smaller size of the hemispheres, but also in a 

 totally different relation of the lobes. Relatively, the under surface of the first lobe of 

 the cerebrum, in the chimpanzee, is much larger than in man ; while, on the other hand, 

 the distance from the most anterior point of the middle lobe to the hindermost point of 

 the posterior lobe is much smaller. In our chimpanzee the distance from the root of the 

 olfactory nerve to the anterior margin of the brain is about 44 millimeti-es, from the point 

 of the middle lobe to the extreme end of the posterior lobe, 69 mm. In the adult man, 

 according to measurements which the first of us has instituted, and which wholly agree 

 with those of the ninth plate of Foville, the first named measurement is 57 mm., the 

 second, 145 mm. In the brain of a new-born child, examined by us, the first dimension 

 amounted to 33 mm., the second to 70 mm. The length of the base of the anterior lobe 

 was thus to the distance from the point of the middle lobe to the end of the posterior 

 lobe, in the chimpanzee, as 1 : 1-52; in the adult man as I : 2-54; in the child, as 

 1 : 2. Hence it appears that the relative proportions of the lobes of the child's brain hold 

 just the mean between the chimpanzee and the adult man ; and that in the course of the 

 growth of the child to manhood, the posterior and middle lobes increase more in length 

 than the base of the anterior lobe. In the orang, the same proportion obtains as in the 

 new-born child or 1 : 2, a residt which is certainly remarkable, and proves that, in this 

 respect, the brain of the orang stands higher than that of the chimpanzee. The second 

 point to which we would direct attention is, that in comparing the brain of man with 

 that of animals, and especially in determining in what manner the cerebellum becomes 

 covered we too exclusively attend to the posterior elongation of the cerebral hemispheres, 

 while the varying size of the cerebellum itself ought to be taken into account. On com- 

 paring the perpeudicular section of the brain of the new-born child (pi. ii., fig. 3.) with 

 fig. 1, the brain of the three-year-old chimpanzee, and with fig. 2, that of the orang of a like 

 age, it is at once apparent that the cerebellum of the orang, and especially of the chim- 

 panzee, is much larger than that of the child ; so that, supposing one could place the 

 cerebellum of the chimpanzee behind the medulla oblongata of the child, it would be even 

 less covered. 



In fact, the distance from the anterior edge of the most anterior part of the cerebellum, 

 close to the corpora quadrigemina, to its posterior margin, measures, in the chimpanzee, 

 38 mm. ; in the orang, 35 mm. ; in the child, 22 mm. If we compare the measure- 

 ments with the whole distance from the anterior to the posterior lobe of the cerebrum, we 

 obtain, according to measurements taken by the first named of us,— 



