1,1 FKVKIt. 



Ih'c-u the cause of tlic suddc-u tlicck of luat prndiutioii. Kiirtlur ••lalK)rafc cxjiiTi- 

 mcntutiou can uIoik* di-U'riiiine positivi-ly how jki luaiunt tht> iiiducnce of the hraiii 

 region noted upon heat production is, hut the drift of the evidence at present is 

 to indicate liuit the effect is temporary, and that the first convoUition does not con- 

 tain the centres which preside over caUiritication, but is in some way connected 

 with these centres so as to exert an influence upon tliem. 



Tlie prohahiiities are that tiie calorific centres arc situated in the pons, and tlnit 

 the power of the first convolution depends upon habitual co-action. Thus, voU- 

 tiou mav habitually use tiie upper cortex spoken of in startinjj the machinery of 

 muscular movement, and along witii tiiis machinery, or even iis u necessary part 

 of it, that of heat production may also be moved. 



The conclusion just reached is in a measure related to tiie vexed question of 

 cerebral localization. It nuiy therefore be allowable to speak of the matter in a 

 little mi>re detail. All of the fun<tions of the nervous centres are, in some of the 

 lower forms of life, concentrated in a single cell, and as the scale of life is ascended 

 the nervous systenr becomes more and more complex by the differentiation of its 

 parts for the more complete performance of functional acts. It is evident that 

 anatomiial and functional dift'erentiation must have at least some relation with one 

 another, and that finally one act must be performed solely by one ])art. It seems 

 inconceivable that a complex mechanism like the liuman c(rel)nvspinal axis should 

 work harmoniously in any ofher way than that certain parts shoidd perform certain 

 nets. This localization of function it will be seen is not the result of an original 

 rigid formation of the mechanism, but is itrol)ably acquired by habitual use for the 

 species, and certainly also to some extent for the individual. .VU parts of the nervous 

 system possess theoretically at least more or less of the original power which resided 

 in the ])rimordial nerve cell, and enabled it to perform various diverse acts. It is con- 

 setiuently perfectly conceivable that when one cell is disabled in the more complex 

 mechanism anothi-r should gradually take on its function: Every physiologist who 

 believes in a respiratory or a vaso-motor centre, if logical, believes also in the principle 

 underlying cerebral localization. With the view of the matter just put forth it is 

 evident tliat degrees of localization must exist. In the dog the speech centre, so far 

 as is known, is not differentiated ; in man it is strictly so. In the same way in the 

 dog the motor centres of the cortex cerebri .seem to have reached only the stage of 

 hal»itual ac'ion, so that when one part of a convolution is removed another can 

 replace it, whilst in the man the motor functions of the cortex appear to be 

 differentiated beyond the stage of habitual action, and one part to lie no longer 

 able to replace another: consequently destructions which produce only evanescent 

 results in the dog catise in the man jHTmanent jiaralyses. 



Having found that there is an apparent connection between the cerebral cortex 

 and the thermic functions of the body, 1 have attempted to discover whether liglit 

 could be thrown upon the truth or falsity of the theories of heat regulation hereto- 

 fore discussed. It will be remembered that the conclusicm was reached that there 

 is either a general vaso-motor centre for the muscular system, situated above the 

 medulla, whicli acts independently of the niedtdlary vaso-motor centres, or else 

 that there is in the pons or alMive it an inhibitory lieat centre. It i> hanlly |>o>" 



