THE EXCITING CAUSE 213 



m various ways, are incessantly undergoing more or less regular dis- 

 placements, renewals or replacements and perhaps in the case of some 

 of them there may actually be a genuine circulation. 



We do not yet know how numerous may be these subtle invisible 

 fluids which are distributed in constant agitation throughout the 

 environment. But we do perceive in the clearest manner that these 

 invisible fluids penetrate every organised body and there accumulate 

 with constant agitation, finally escaping in turn after being retained 

 for a longer or shorter period. They thus stimulate movements and 

 life, when they come in contact with an order of things permitting of 

 such results. 



With regard to such of these invisible fluids as chiefly constitute 

 the exciting cause under consideration, two of them appear to us to be 

 the essential elements of this cause, viz. caloric and the electric fltiid. 

 They are the direct agents which produce orgasm and the internal 

 movements which in organised bodies constitute and maintain hfe. 



Caloric appears to be that of the two exciting fluids in question 

 which causes and maintains the orgasm of the supple parts of Hving 

 bodies ; and the electric fluid is apparently that which provides the 

 cause of the organic movements and activities of animals. 



My justification for this division of the faculties assigned to the two 

 fluids in question is based on the following principles. 



In inflammations, the orgasm acquires an excessive energy which is 

 at length even destructive of the parts. This is clearly in consequence 

 of the extreme heat developed in inflamed organs : it is, then, especially 

 to caloric that the orgasm must be attributed. 



The rapidity of the movements of caloric throughout the bodies 

 which it penetrates is very far from equalHng the extraordinary speed 

 of the movements of the electric fluid. Hence this latter fluid must 

 be the cause of the movements and activities of animals ; it must be 

 more particularly the genuine exciting fluid. 



It is possible, however, that other active invisible fluids combine 

 with the two already named in the composition of the exciting cause ; 

 but what appears to me beyond question is that caloric and electricity 

 are the two chief components, and perhaps even the only components 

 of this cause^ 



In animals with low organisations, the caloric of the environment 

 seems to be sufficient by itself for the orgasm and irritabiUty of their 

 bodies ; hence it arises that in extreme reductions of temperature and 

 in the winters of cHmates in high latitudes, some entirely perish while 

 others become more or less completely torpid. In these same animals 

 the ordinary electric fluid provided by the environment appears to be 

 stifficient for the organic movements and activities. 



