38 PROTEOLYTIC PANCREATIC FERMENT 



the general circulation and fails to pass to the pancreas. A 

 number of authors, especially those of the Pawlow school, 

 are disposed to assume that the pancreatic secretion is gov- 

 erned by a dual mechanism, partly nervous and partly 

 humoral. 7 



Secretin seems to be a thermostabile substance, soluble 

 in alcohol, not specific for any particular kind of animal, but 

 apparently identical in all vertebrates. The belief that it is 

 formed from a "prosecretin" when acid comes in contact 

 with the intestinal mucosa is improbable, as it can be 

 shown 8 that solutions having secretin-like influence may be 

 obtained by treating the mucous membrane of the intestine 

 with sodium chloride solution, soaps, alcohol, peptone, 

 chloral hydrate or even with hot water ; the usual employ- 

 ment of mineral acids is readily explicable from the fact that 

 such an agent prevents the destruction or masking of the 

 secretin action by other agents contained in the extracts of 

 intestinal mucous membrane. Fleig's assumption of the 

 necessity of recognizing different kinds of secretin ("sapo- 

 krinin," * ' ethylokrinin, ' ' etc.), according to the method of 

 derivation, is probably not justified. 9 



Secretin and Cholin and the Vasodilatms. From an 

 investigation which the author's friend, Carl Schwarz, 10 

 and the author conducted, it was found that cholin exists 

 in the secretin prepared according to the method of 

 Bayliss and Starling. The influence of such an extract 

 is unquestionably to be partly attributed to this base, 



T Cf. A. Bylina (Institut. exp. Med., St. Petersburg), Pfliiger's Arch., 142, 

 531, 1911. 



* Delezennes, and Pozerski, Fleig, Camus, Falloise, Gley and others. 



8 While C. Delezennes and E. Pozerski, Journ. de Physiol., 14, 521, 540, 1912, 

 in their most recent publications insist upon the non-existence of a " pro- 

 secretin," W. Stepp (Univ. College, London: Journ. of Physiol., 43, 441, 1912) 

 holds that secretin practically always is to be found in the intestinal mucous 

 membrane as prosecretin, free secretin being found only occasionally in small 

 quantities; cf. also S. Lalou, Journ. de Physiol., 14, 241, 465, 530, 1912; E. 

 Gley, ibid., 507. 



10 O. v. Fttrth and C. Schwarz, Pflliger's Arch., 124, 427, 1908; cf. Litera- 

 ture thereto appended. 



