152 Dr. Grimbaum and Prof. Sherrington. [May 25, 



"Observations on the Physiology of the Cerebral Cortex of the 

 Anthropoid Apes." By A. S. F. GRUNBAUM, M.D., F.K.C.P., 

 and C. S. SHERRINGTON, M.A. ; M.D., F.PuS. Keceived May 25, 

 -Bead June 11, 1903. 



(From the Physiological Laboratory, University of Liverpool.) 



Since presenting our former note on this subject, we have obtained 

 some further observations, though the number is still less than we 

 should wish, owing to the rarity and expense of the material. Our 

 further observations have been upon five chimpanzees of the commoner 

 variety, and upon one more orang. 



The statements given in our former communication have been con- 

 firmed in ail respects by our observations obtained since then. We 

 can, further, now make the following statements in addition : 



The whole of the surface of the " island of lieil " has proved 

 " inexcitable " under faradisation with currents even considerably more 

 intense than those sufficing to excite muscular movements when applied 

 to the pre-central convolution. This is noteworthy because the large 

 extent of the insula is a character distinguishing the brain of the 

 anthropoid apes from that of the lower apes, and bringing it nearer 

 toward the human type. 



Faradisation of the cortex of the inferior frontal convolution in either 

 hemisphere has failed in our hands so far to elicit movements of any 

 satisfactory degree of regularity or constancy; and this even under 

 use of currents much stronger than those which suffice when applied to 

 the " motor " cortex proper. The movements for which, in particular, 

 careful search was made, were those connected with vocalisation. From 

 the posterior region of the convolution, at scattered points, and without 

 constancy even at them, strong faradisation occasionally seemed to 

 induce movements in the larynx, distinguishable from the rhythmic of 

 respiratory origin. Judging from such evidence as we altogether 

 obtained, we conclude that either (1) no Broca "speech centre," at all 

 distantly foreshadowing the human, exists in these anthropoid brains, 

 or (2) that direct faradisation of the Broca speech cortex is inefficient 

 itself to evoke vocalisation. These two inferences, are, of course, not 

 mutually exclusive, and both the suppositions may be correct. 



Repeated observations on excitation of the cortex of the pre-centrai 

 convolution confirm an opinion we had formed at the time of our 

 former communication, and indicated in the diagram then furnished, 

 but not verbally expressed. This is to the effect that the anterior 

 limit of the " motor " field is not of sharp, abrupt character, but fades 

 off forward somewhat gradually. This edge extends further forward 

 under Bahnung." Under general conditions producing lowered 



