346 PULMONARY MUCOUS TISSUE. 



artificially kept np (a process which induces cooling, if too 

 energetically performed), observed that the temperature was 

 considerably lowered, and thence formed the opinion tnat 

 calorification is due to a more or less mysterious influence of 

 the nervous system. It has been since discovered that the 

 cerebro-spinal nervous system modifies the production of 

 animal heat by acting on the tissues and giving rise to the 

 chemical processes of oxidation and separation which accom- 

 pany their vital manifestations. 



The effect produced by the great sympathetic nerve on 

 calorification is not, however, yet fully decided. We know 

 that if this nerve be divided or paralyzed, hyperaemia of the 

 corresponding parts of the body follows, and is accompanied 

 by a rise in the temperature. On the other hand, galvanization 

 of the peripheral extremity of the great sympathetic nerve 

 causes anaemia of the corresponding parts, accompanied by a 

 fall in the temperature (see p. 170). Are these changes of 

 temperature simply due to a more or less considerable afflux 

 of blood, which forms the vehicle of the heat produced in the 

 principal internal seats of combustion (the liver, the spleen, and 

 the viscera in general), or does the great sympathetic nerve pro- 

 duce any immediate effect upon calorification, beyond the 

 influence exercised by its vaso-motor network? This is a 

 much disputed question, and very difficult to answer. Claude 

 Bernard first directed attention to the subject of the great 

 sympathetic nerve, and its influence on the circulation and on 

 the temperature of the parts through which it passes; and he has 

 lately resumed the investigations which have already yielded 

 such abundant fruits, seeking especially to determine the calor- 

 ific function of this nerve (course of 1872). 1 This question brings 

 us back to the much controverted subject of the trophic 

 nerves . " Some physiologists have supposed that there exists 

 a third class of nerves (beside the sensory and the motor), 

 called trophic nerves; that these immediately govern the 

 phenomena of interior nutrition, and regulate the exchanges 

 which occur in the deep tissues, and which constitute the 

 assimilation and dis-assimilation (constructive and destructive 

 metamorphoses) of the elements. Their existence has never 

 been demonstrated by anatomy, and physiology and patho- 

 logy have not yet sufficiently proved their necessity" (Cl. 

 Bernard). Claude Bernard, however, seems, after all, to 

 attribute to the great sympathetic nerve some office of this 



1 " Revue des Cours Seientifiques. " Mai et juin, 1872. 



