Chap, ii.] OP THE PROCESSES OF ORGANIC CALORIFICATION. 465 



animal has then become cold-blooded. Moreover, we can obtain 

 the same result by various processes : by directly and gradually 

 cooling the animal,^ by rendering it immobile for a considerable 

 time, by subjecting it to rocking movements, by covering it with 

 an impenetrable varnish. 



The action of physical and psychical sensibility also tells upon 

 the capillary circulation through the medium of the spinal 

 marrow and of the vaso-motory nerves. Experiments made by 

 Professor P. Mantegazza upon man and animals have proved 

 that physical pain provokes a lowering of the temperature. It is 

 often the same with moral pain, sombre passions, prolonged 

 griefs, which sometimes end by impairing the nutrition of the 

 tissues and cause organic degenerations. 



Organic heat, then, is the result of nutrition, of life itself. 

 Every organised body, especially every animal, is a fireplace, 

 where diverse substances, mostly ternary or quaternary, burn 

 slowly, developing heat which, in its turn, provokes or forms the 

 exchanges, the chemical metamorphoses necessary to life. A 

 very large proportion of organic heat is engendered by the action 

 of oxygen upon the living solids and liquids. It is this dominant 

 chemical action which gives the impulse to all the others, when 

 it is not directly the only calorific source. Many other chemical 

 reactions take place in the organisms, and also engender heat. 

 " The albuminoidal substances produce decided calorific pheno- 

 mena, at the time of their hydratation with evolvement, or of 

 their dehydratation with combination. The hydrates of carbon 

 (sugar, starch, &c., &c.) can disengage heat by simple evolvement 

 independently of any .oxydation. Finally, the neutral fat bodies 

 can also give heat in evolvement by simple hydratation, as 

 appears to take place under the influence of the pancreatic 

 juice."^ 



1 Fourcault, Influence desEnduits ImpermSaUes {Oomptes Bendus de VJcad. 

 des Sc, t. XVI.). 



' Berthelot, De la Chaleur Animale {Journal d'Anat. et de Physiol., t II,, 

 p. 671). 



