422 FUNCTIONS OF THE NERVES. [ch. hi. 



eminent writers, who have sought for the source of animal 

 heat in the nerves^ and not in the friction of the particles of 

 the blood with each other, or with the sides of the vessels. 

 Amongst these were Caverhill^ and Roederer.^ Wrisberg^ 

 followed the latter, and seems to have wished to corroborate 

 his doctrine by his own arguments and observations. In 

 comparing animals with vegetables, he saw that it was the 

 nervous system that was wanting in the one and present in 

 the other ; and since animal heat was enjoyed by animals, and 

 not by vegetables, it seemed to him that there existed some 

 connection, between a nervous system and animal heat. 

 Further, he thought this was confirmed by the fact, that the 

 passions, which excite the nervous system, increase animal 

 heat, but that those which depress the nervous system induce 

 cold. In further corroboration he observes, that if the back be 

 turned towards the fire, and the spinal marrow warmed, warmth 

 is rapidly transmitted along the nerves arising from it to all 

 parts of the body ; while, on the contrary, if the front of the 

 body be towards the fire, the body is not warmed so quickly. 

 Thaer also thought that this theory of the dependence of the 

 animal heat upon the operation of the nerves, was not deficient 

 in probability.* Musgrave also maintained, that animal heat 

 arises neither from the intestine motion of the fermenting 

 blood, nor from the friction of the blood against the sides of 

 the vessels, but from irritation of the nerves, whether from an 

 external agent applied to the nerves, as in inflammation, or an 

 internal irritant, as anger.^ La Roche was of the same opinion, 

 and attempted to reconcile his views with those of Haller, for 

 he conjectured, with Newton, that the nervous fluid is aetherial, 

 and that its oscillatory motion in the nerves is the proximate 

 cause of animal heat, the circulatory motion of the blood in 

 the vessels being only secondary, and by continually stimulating 

 the nerves, exciting the oscillation of the nervous fluid in them; 



1 In Haller. de Part. Corp. Hum. Fabr. et Usu, torn, iv, p. 248. 



2 In Programmate de Animalium Galore. Ad Diss. CI. Grimm, de Visu. Got- 

 tingse, 1758. 



3 In Program, de Respiratione prima, Nervo phrenico, et Calore animali. 

 Gottingae, 1763. It has also been printed in Sandifort's ♦Thesaurus Diss. Med.,' 

 tom. ii. 



* De Actione Systematis Nervosi in Febribus. Gottingae, 1774, p. 83. 

 ' Op. citato. 



