26 ROYAL SOCIETY OF CANADA 



He kept the experimental room at *75° F., and exposed both hemi- 

 spheres fully, keeping the brain covered with absorbent cotton-wool 

 when not being stimulated. 



The only clue I can find to the reason for this difference in the 

 method of treating the cat and the rabbit occurs in a sentence in which 

 the work of another is referred to (p. 24) : ' I failed to produce acceler- 

 ated breathing in non-anaesthetized animals." 



Ferrier, speaking of stimulation, says : •' Though it is obviously 

 advisable to use no stronger current than is sufficient to produce a defin- 

 ite result, the measure of the intensity of the stimulus to be employed 

 in each case is the degree of definite and decided localization of eftects 

 uniformly attainable." 



He also says : " That (current) which will cause intense and indefin- 

 ite action in an animal non-narcotized, will excite only moderate and 

 definite action in an animal sufficiently narcotized to abolish all sense of 

 pain, and no efiect at all on an animal deeply anaesthetized." 



I do not find that Ferrier anywhere recommends experimenting on 

 non-narcotized animals, and from the last quotation I should suppose 

 that he would be sceptical, to say the least, of results obtained in non- 

 anœsthetized animals. 



From a large experience in experimenting on the brains of animals, 

 I can fully endorse all that is expressed in the quotations from Ferrier. 

 Only experience can determine what degree of anaesthesia and what 

 strength of current suit best. 



M}' own methods in the determination of cerebral localization have 

 been described in my paper on "The Functional Development of the 

 Cerebral Cortex," ' so that onl}' a brief reference need be made to them 

 here. 



The animals used, of whatever kind, were given ether. When fully 

 under its influence the brain was exposed as rapidly and with regard to 

 as little loss of blood, exposure to the air and other unfavourable condi- 

 tions as possible. 



It is true, as has been pointed out by Fiirstner,'' and quoted by 

 Mann, that some movements may be induced by weaker currents than 

 others, but following Ferriers dictum, already quoted in regard to cur- 

 rent, one centre may be compared with another under the same or very 

 similar conditions without any danger of fallacy. 



Mann states that he left his rabbits thirty to sixty minutes for the 

 ether narcosis to pass ofi". Ether narcosis, as everyone knows, is com- 

 j.aratively transient, and it is because of this that 1 have used it invariably 

 when conducting localization researches on the brain. Very frequently 



' These Transaction.s for the current year. 



2"Exper. Beitrag, z. Electrisch. Kei/. d. Hirnrinde " Arch f. P.sych. vi. pp 

 719-732. 



