Thr Kxcitnblt' Loricx of llif C'liiiu|>an/.«»e. Oning rtan. aii«l Corilla \'M 



the cortex is prevention of a fail in temperatun* of the exi)o.se<l cortical 

 surface, 'i'ho temperature of the room was therefore always kept high, 

 usually fully 30° C: and tlie cortex was kept as far as j>ossihl»; covered 

 with cotton- wool swabs wrun<; out alter beinj; soaked with IxH-kes fluid 

 at 8.S V. 



For recording: at the time of the experiineiu ilie localisation of the 

 points stimulated and the responses obtained, the followiiifj plan was 

 adopted. When the cortex had been exjjosi-d after the suburachnoid lluid 

 had been evacuated, a thin ijlass plate warmed to rather al)ove blood 

 temperature was laid over the exposed cortex. The lines of the sulci were 

 then traced on the jrlass, and also the lines of the lar«rer arteries and veins. 

 The drawing on the i^lass was then traced on millimetre-b(juared tracing 

 paper. On this map, as the point-to-point examination of the cortex pro- 

 ceeded, an observer then wrote numerals indicating each point stimulated 

 at the point on the map corresp<jnding w ith tiie point stimulated. Another 

 observer listed the responses obtained, entering each response on liis list 

 opposite a numeral corresponding with that locating on tlie map the po.si- 

 tion of the point wliich evoked it when stimulated. 



Ablations were performed with the low-tempered knife recommended 

 by Mott: the blade of this knife can be bent to any curve desired at the 

 time. A number of the ablation experiments were performed under aseptic 

 precautions of the usual kind and the animals allowed to recovei-. Their 

 details are given below under the separate experiments. 



The animal used was for the most part the chimpanzee, Anthropo- 

 pithecus troglodytes. Among the specimens was one of the bald variety, 

 A. trogl. calv us, the variety to which belonged the well-known " Sally," 

 observations upon which were made by (J. J. Romanes. Two others were 

 of the variety known as Kola-kaamba by the dealers. The convolutional 

 pattern of the Rolandic region of tlie hemisphere of our specimen of Calvus 

 is given in tig. (i, B; v. infra. Besides the chimpanzees, three orang-utan 

 (Simia satyrus) and three gorillas (CJorilla savagei) were used. 



n. EXI'KRIMEXTS P.V StIMUL.VTIUN. 



1. Prefatory Remarks on the Motor Responses obtained 



and their Localisation. 



Regarding the subjoined list (p. 148) of movements obtained in response 

 to localised faradisation of the cortex, they are recorded in all cases in the 

 notation made at the time by an observer entrusted solely with the 

 observation of them, the management of the stimulation and the recording 

 of the point stimulated upon the previously prepared map being in other 

 hands for that time. In some cases there appear in the list notations 

 which are not detailed, e.g. " mouth " : such instances mean that the 

 observer, though seeing that a movement of the mouth had occurred did 

 not feel able to say what that movement had been exactly, and that on 



