SECT, v.] INFLUENCE OF NERVES IN SECRETION. 419 



In truths since it has been shown how great is the influence 

 of the nerves on the vessels, in virtue of which stimuli can 

 excite a more copious flow of fluids to a part, we infer that the 

 same thing occurs in the secreting viscera, which consist 

 almost entirely of vessels. So soon, therefore, as by nervous 

 action the fluids are more copiously attracted to secreting 

 viscera, the secretions are necessarily increased. Moreover, 

 since the nerves have the property of causing spasms, or con- 

 traction of the capillaries, it is manifest that the secretions 

 may be diminished, or entirely interrupted by the influence of 

 the nerves, the secreting vessels being entirely closed by con- 

 striction. Illustrations, confirmatory of this doctrine, have 

 been already brought forward. 



But it may further be asked, is the influence of the nerves 

 on the fluids so great, either at the time of secretion, or when 

 secreted, that it can modify, or alter them, or entirely change their 

 nature ? Thaer^ seems to have held an opinion somewhat to this 

 eff'ect, when he observes, that in fevers the blood becomes some- 

 times putrid and dissolved, sometimes acrid, again imperfectly 

 coagulable, or in some other way altogether changed from the 

 healthy condition preceding the fever. Musgrave^ attempts 

 to prove, from many facts, that the fluids are vitiated by 

 irritation of the nerves. In the first place, he brings forward 

 the experiments of Haller, who observed the contents of 

 the stomachs of rabbits to become putrid and thoroughly 

 tainted, in a short time, after tying the eighth pair of nerves ; 

 and that a very ofi*ensive suppuration was also brought on in 

 the foot by tying the nerve. Next, he shows that a vomiting 

 of fetid bilious matter has been excited by an afi'ection of the 

 head, and by the irritation of calculi passing along the ureters. 

 Further, diarrhoea is often excited by mental emotion, and this, 

 indeed, because that afi'ection of the nerves renders the secre- 

 tions more acrid and loose. The milk of a nurse, aff'ected 

 with anger, immediately acquires an unpleasant taste, and 

 becomes injurious to the child. The bite of an enraged animal 

 is difficult to cure, and is often followed by bad consequences. 

 He thinks he can explain why, when blood is drawn, it is 

 often inflammatory in the first cups, and less so in the later, 



' De Usu System. Nervosi in Febribus, § xxxviii. 

 * Betrachlung iiber die Nerven, 3ten Hauptst. 



