ROLLESTON ON THE BKAIN OF THE ORANG UTAXG. 203 



power of discovering the third class of differences, we are indebted to 

 M. Gratiolet's masterly analysis of the cerebral convolutions. Pre- 

 viously to the appearance of the "Memoirc but les Plis Cerebraux de 

 1' homnie et des Primates," it was all but impossible to express in words 

 the differences which the eye detected in the arrangement in two dif- 

 ferent brains of what has been called "the chaos of the convolutions." 

 What was previously all but an impossibility, M. Gratiolet's philosophy 

 has made an easy task. No apology can be necessary for adopting his 

 phraseology, as the right of naming the country he has conquered, is a 

 prerogative never denied to one, who has succeeded in subduing a terri- 

 tory which few before him had even thought of invading. 



Under our fourth head we shall arrange those points of difference 

 which a dissection of the brain alone can reveal. 



These four heads correspond, it is obvious, to the successive stages of 

 an anatomical investigation ; and they possess, consequently, the merit 

 not merely of colligating conveniently the results, but also of corre- 

 sponding accurately to the several processes of an accurate anatomical 

 investigation. 



The orang dissected was a young male {Si mi a Morio). The first two 

 molars had just come into use in both jaws; the weight of the entire 

 body was but 16 lbs. 12 oz. ; the height was 2 feet 7 inches. None of the 

 internal viscera presented any appearance of disease. The lungs, which 

 were both but unilobar, were crepitant throughout, free from conges- 

 tion, collapse, or tubercle. The callosities on the backs of the fingers, 

 which have been held, and with some show of probability, to indicate 

 the existence of a state of debility, were absent. 



The roof of the cranium was removed by a circular incision, inter- 

 secting the foramen magnum posteriorly. Before the removal of the 

 dura mater, the cerebral hemispheres were seen to cover the superior 

 surface of the cerebellum entirely, and even to project a very little way 

 beyond it, posteriorly. After the removal of the dura mater, a small 

 segment of cerebellar surface became visible on each side, posteriorly to 

 the tips of the occipital lobes. It is well known* that the anteropos- 

 terior dimensions of the corpus callosum are very different in a brain 

 whilst contained and supported within its case, and when removed from 

 the skull, — the forward swaying of the hemispheres upon their support- 

 ing stems, the crura, flattening the previously arched commissure. That 

 it was the weight of the hemispheres, working similarly, which produced 

 the alteration just noted in the relations of the cerebrum to the cere- 

 bellum was seen thus A wider segment of cerebellar surface ivas visible 



on the left side than on the right, the anifnal lying over towards its right 

 side. 



* "Bei der Messung der Lange des Balkens muss man wohl im Auge behalten dass man 

 ihn Misstso lange die Hemispbaren ihre Lage noch in Schadel haben ; am herausgenom- 

 menen Gehirn dehnt er sich sebr betractlich in die Lange aus und veriiert seine "Wol- 

 bung." Huscbke. Schaedel, Him und Seele, p. 110. 



