742 FEED C. KOCH 



This view was soon considered incorrect, first, because of similar results 

 with all nerve connections supposedly cut, and, second, in view of the 

 secretory effect of intravenously introduced acid extracts of the duodenum, 

 as first shown in 1902 by Bayliss and Starling (a). Popielski, however, 

 called attention to the general distribution of this activity when acid ex- 

 tracts of tissues are made ; and claimed that we are not here dealing with 

 the action of a true specific secretagogue, but with a general vasodilator 

 phenomenon due to a substance he called "vasodilatin." Many of the 

 earlier workers were inclined to consider cholin as the truly active con- 

 stituent, but in recent years the evidence appears to be distinctly against 

 that view, and tending to acceptance of the view that the active substance 

 may be betaimidazolethylamin or histamin. We can summarize the 

 studies on this subject most satisfactorily under the following headings: 

 (a) specificity of distribution of secret in activity; (b) specificity as to 

 site of action ; (c) specific chemical character of secretin ; (d) physiological 

 evidence as to the presence of secretin in the blood and as to its mode of 

 action; (e) relation of secretin to the internal secretion of the pancreas; 

 (f) other supposed physiological actions; (g) clinical applications. 



Specificity of Distribution of Secretin. Bayliss and Starling (1902) 

 found the secretagogue activity in preparations of the duodenum, some- 

 what in the jejunum, almost absent in the ileum and entirely absent in 

 the salivary glands, liver, spleen, pancreas, kidney and tongue; but one 

 must bear in mind that all of their studies were conducted on anesthetized 

 animals. Furthermore, in an attempt to meet Popielski's criticism, the 

 authors tried to remove vasodilatin by absolute alcohol extraction and then 

 used the alcohol insoluble residue as a purer form of secretin. In this 

 -process they neither removed the vasodilatin or depressor action com- 

 pletely, nor are they certain that they did not also remove some of the 

 true secretin in the- alcohol extraction process, In fact, the purer secretin 

 solution not only showed a less marked depressor action, but also a dis- 

 tinctly lowered secretagogue activity. Camus (1902) reported that large 

 doses of an acid maceration of mesenteric ganglia from the rat stimulated 

 the pancreas to secretion. Popielski claims that all blood pressure lower- 

 ing extracts, if they cause a vasodilatation together with decreased coagula- 

 bility of the blood, bring about the same secretion. It is, of course, well 

 known that most of the tissues when extracted with dilute acids or water 

 yield a blood pressure lowering solution, nevertheless Popielski has by no 

 means satisfactorily confirmed his claims by experimental observations. 

 Matsuo reports results similar to those of Bayliss and Starling and adds 

 that Witte's peptone, heart muscle, kidney and lung extracts are inactive. 

 F. Sodre and G. Stodel find the absolute alcohol extracts of Witte's peptone 

 in doses of 0.02 gram per kilo body weight to cause no appreciable 

 secretion as compared with duodenal secretin solutions. They also found 

 commercial silk and egg peptones equally inactive. Rogers, Rahe, Fawcett 



