214 ZOOLOGICAL PHILOSOPHY 



The case is different with regard to animals of highly complex organisa- 

 tions : in these, the caloric of the environment merely completes or 

 rather aids and favours the power which these living bodies themselves 

 possess of constantly producing caloric within them. It is probable 

 even that this internally produced caloric has undergone modifications 

 in the animal as a result of which it is specialised ; and rendered alone 

 suitable for the maintenance of orgasm ; for when the state of the 

 organisation has greatly enfeebled the orgasm and irritability, the 

 external caloric arising either from our fires or from a rise of tempera- 

 ture cannot take the place of internal caloric. 



The same observation appears to be applicable also to the electric 

 fluid which excites the movements and activities of animals with 

 highly complex organisations. It appears indeed that this electric 

 fluid, which is introduced through the medium of respiration or of 

 food, has undergone some modification in the animal's interior and 

 become transformed into nervous or galvanic fluids. 



As to caloric, it is unquestionably one of the principal elements 

 of the exciting cause of life, and is particularly instrumental in pro- 

 ducing and maintaining orgasm, without which life could not exist. 

 So true is this that a great reduction of temperature would exterminate 

 all living bodies long before reaching the point of absolute cold. As a 

 matter of fact, the cold of our winters, especially when it is extreme, 

 causes the death of a great many of the animals exposed to it. But 

 we know that on no part of the earth's surface and at no period of the 

 year do we ever find a total absence of caloric. 



Let me repeat that without a special exciting cause of orgasm and 

 vital movements — without the force which alone can produce such 

 movements — life could not exist in any body. Now this exciting 

 cause has nothing to do with the visible fluids of living bodies, nor 

 with the solid containing parts of these bodies. This is a fact that can 

 no longer be questioned since it is justified by all observation. 



This same exciting cause is also the cause of fermentation, the mani- 

 festations of which it alone brings about in all compound non-hving 

 matter, whose parts are favourable to it. Thus in great reductions 

 of temperature the activities of life and fermentation are suspended 

 more or less completely, in proportion to the intensity of the cold. 



Although hfe and fermentation are two very different phenomena, 

 they both derive from the same origin the movements by which they 

 are constituted ; and in both cases it is necessary that the state of 

 the parts, whether of the organic body capable of life or of the inorganic 

 body capable of fermentation, should be favourable to the performance 

 of these movements. But in bodies possessing life, the existing order 

 and state of things are such that every decomposition of principles 



