326 



SCIENCE. 



Tribune in these cases, which were submitted to the 

 authors on the 4th of December last for correction or re- 

 jection ; no objection being made we printed them in a 

 recent number. After publication Professor Agassiz now 

 writes that the reports under his name are not satisfactory 

 to him. We therefore request our readers to consider 

 them withdrawn. 



Professor George F. Barker, Professor O. C. Marsh 

 and Professor J. E. Hilgard are preparing more elaborate 

 reports of their important papers, and promise them at 

 an early day. 



THE BRAIN OF THE ORANG.* 



BY HENRY C. CHAPMAN, M.D. 



The brain of the Orang has been figured by Tiede- 

 mann, Sandifort, Schroeder van der Kolk and Vrolik, 

 Gratiolet, Rolleston, etc. On account, however, of the 

 few illustrations extant, and of the importance of the 

 subject, I avail myself of the opportunity of presenting 

 several views of my Orang's brain (Figs. 1 to 5), which 

 was removed from the skull only a few hours after 

 death. The membranes were in a high state of conges- 

 tion, and a little of the surface of the left hemisphere had 

 been disorganized by disease, otherwise the brain was in 

 good condition. It weighed exactly ten ounces. The 

 brain of the Orang in its general contour resembled that 

 of man more than those of either of the Chimpanzees 

 which I examined. In these the brain was more elong- 

 ated. The general character of the folds and fissures in 



Fig. i. 



the brain of the Orang, Chimpanzee, and man are the 

 same ; there are certain minor differences, however, in '• 

 their disposition in all three. The fissure of Sylvius in 

 the Orang runs up and clown the posterior branch pur- 

 suing only a slightly backward direction; the anterior 

 branch is small. The fissure of Rolando, or central fis- 

 sure, quite apparent, is, however, situated slightly more j 

 forward in the Orang than in man. It differentiates the 

 frontal from the parietal lobe. The paiieto-occipital fis- 

 pure is well marked ; bordered externally by the first oc- 

 cipital fold it descends internally on the mesial side of the 

 hemisphere, separating the parietal from the occipal lobes. 



I r ,111 the Proceedings of the Academy of Natural Sciences, I'hilsi.,iE 



in the Orang, the parieto-occipital fissure does not reach 

 the calcarine, being separated from it by the "deuxieme 

 plis de passage interne" of Gratiolet, or " untere innere 

 Scheitelbogen-Windung " of Bischoff. I have noticed this 

 separation as an anomaly more than once in man. 



According to Bischoff, this disposition obtains in the 

 Gorilla, and seems to be usual also in the Chimpanzee. 

 In the female Chimpanzee, however, on the left side 1 

 found the parieto-occipital fissure passing into the cal- 

 carine, as in man. The frontal lobe is easily distin- 

 guished from the parietal by the fissure of Rolando, and 

 from the temporal by the fissure of Sylvius. In the 

 Orang it is higher, wider, and more arched than in the 

 Chimpanzee. The anterior central convolution in front 

 of the central fissure runs into the post-central convolu- 

 tion above and below, as in man. It is difficult, however, 

 to identify the three frontal convolutions seen in man and 

 the Chimpanzee, the frontal lobe of the Orang dividing 

 rather into two convolutions, the middle one being badly 

 defined. This is due somewhat to the length of the pre- 

 central fissure, which is as long as the fissure of Rolando, 

 extending farther upward than in man. There was 

 nothing particularly noticeable about the base of the 

 frontal lobe ; on the mesial surface it ran into the 

 parietal. The part above the calloso-marginal fissure in 

 the Orang is not as distinctly divided into convolutions as 

 in man, though these are not constantly present even in 

 all human brains. The parietal lobe is separated from 

 the frontal by the central fissure, from the occipital and 

 temporal incompletely, by the parieto-occipital and 

 Sylvian fissures. The posterior-central convolution is 

 well defined. The parietal fissure in the Orang is more 

 striking than that of man, resembling the Gorilla's; it is 

 twice as long as the corresponding fissure in the Chim- 

 panzee, extending from the transverse occipital fissure, as 

 is sometimes the case in man, almost into the fissure of 

 Rolando. Jt is unbridged and without a break, and 

 divides the parietal lobe completely into upper and lower 

 parietal lobules. The upper parietal lobule is bounded 

 externally by the parietal fissure ; posteriorly it is sep- 

 arated from the occipital lobe, internally by the parieto- 



I'lC. 2. 



occipital fissure ; externally it is continuous with the oc- 

 cipital lobe, as the first occipital gyrus, anteriorly it is 

 separated from the posterior central convolution more 

 completely than in mar, by a fissure which runs paralled 

 with the central fissure. There is in the Orang, also, a 

 fissure running paralled with the parietal, which sub- 

 divides the upper parietal lobule into inner and outer 

 portions. The precuneus, or the space on the mesial 

 side of the parietal lobe between the parieto-occipital 



