STRUCTURE OF SECRETING ORGANS. 33 



Mental emotions, pain, and various circumstances, the 

 influence of which upon secretion has long been observed, 

 operate through the nervous system. Numerous familiar 

 instances of this kind are quoted in works on physiology : 

 such as the secretion of tears ; arrest or production of the sali- 

 vary secretions ; sudden arrest of the secretion of the mam- 

 mary glands, from violent emotion ; increase in the secretion 

 of the kidneys or of the intestinal tract, from fear or anxiety ; 

 with other examples which it is unnecessary to ennumerate. 



The effects, upon some of the secretory organs, of de- 

 struction of the nerves distributed to their parenchyma 

 are very curious and interesting. Miiller and Peipers 

 destroyed the nerves distributed to the kidney, and found 

 that not only was the secretion arrested in the great ma- 

 jority of instances, but that the tissue of the kidneys be- 

 came softened and broken down. 1 These experiments have 

 been lately repeated by Bernard. He found that animals 

 operated upon in this way died, and that the tissue of the 

 kidney was broken down into a fetid, semifluid mass. After 

 division of the nerves of the salivary glands, the organs be- 

 came atrophied, but did not undergo the peculiar putrefac- 

 tive change which was observed in the kidneys. The same 

 effect was produced when the nerve was paralyzed by in- 

 troducing a few drops of a solution of woorara at the origin 

 of the little artery which is distributed to the submaxillary 

 gland. 3 



General Structure of Secreting Organs. In treating of 

 the mechanism of secretion and excretion, it has been evi- 

 dent that all glandular organs must be supplied with blood 

 to furnish the materials for secretion, and be provided with 

 epithelium, which changes these matters into the characteris- 

 tic elements of the secretions. We can understand how cer- 



1 MUELLER, Manuel de physiologic, Paris, 1851, tome i.,p. 391. 

 8 BERNARD, Lefonssur les proprietes des tissus vivant*, Paris, 1866, p. 399. 

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