994 EXPERIMENT ST/.TION RECORD. 



secretin on tlie action of tiie pancreas. The results obtained showed that this body 

 stininlateH the pancreas to secrete a juice containinji all the enzyms present in the 

 gland at the moment. "The amount and nature of the ferments, which are present 

 in and secreted by tln^ pancreas at any moment depend not on the action of secretin, 

 but on the previous diet of the animal, and are quite independent of secretin. 



"The existence of a chemical mechanism for the adaptation of tlie pancreas is 

 merely a natural corollary to the chemical mechanism of normal i)ancreatic secre- 

 tion. . . . But the mechanism, though in each case chemical, is not of exactly 

 the same nature; the stimulus of secretin calls forth an immediate response on the 

 part of the pancreas, whereas the specific stimulus of the food stuff has a slower, but 

 more prolonged effect. 



"Hence, secretin evokes the secretion by the pancreas of all the different enzyms 

 present in the pancreas at the time; and the actual composition of the juice as 

 regards its ferments for any given meal depends mainly on the previous diet of the 

 animal, and little if at all on the nature of that particular meal, except in so far as 

 the nature of the food determines the amount of hydrochloric acid secreted by the 

 stomach. 



"The influence of diet in modifying the nature and amount of the enzyms secreted 

 by the pancreas has some bearing on the time of appearance of the ferments after 

 birth. Apparently lactase is not present in the pancreas at birth, although it makes 

 its appearance certainly within 10 days, and in all probability earlier." 



The peptone-splitting ferments of the pancreas and intestine, H. M. Vernon 

 {Jour. Physiol., 30 (1903), No. 3-4, PP- 330~3G9, dgms. 5).— The questions studied 

 include the rate of development of the biuret reaction, the law of action of peptone- 

 splitting ferments, the differentiation of trypsin and pancreatic erepsin, the action of 

 peptone-splitting ferments on native proteids and related topics. Among the author's 

 deductions are the following: 



"The peptone-splitting power of ferments can be estimated colorimetrically by 

 means of the biuret test. If, for instance, twice as great a volume of the partially 

 digested peptone folution as of the undigested peptone is needed to give the same 

 tint with alkaline copper sulphate when observed in a colorimeter, then 50 per cent 

 of the peptone must have been split up by ferment action. It was found that the 

 biuret reaction took an appreciable time to develop its maximum tint. . . . 



"It was found that the time required to split up any given percentage of the pep- 

 tone varied inversely as the quantity of ferment. ... Of the peptone splitting 

 effected by pancreatic extracts the larger part is due to pancreatic erepsin, a ferment 

 entirely distinct from trypsin. Thus extracts which have little or no fibrin-digesting 

 power, owing to the existence of the trypsin in the zymogen form, have a consider- 

 able peptone-splitting action. When the trypsin has become liberated from the 

 trypsinogen the extract may have twice as rapid an initial action on peptone, but the 

 amount of peptone splitting ultimately accomplished by it is always smaller than 

 that by the zymogen extract. This is presumably due to the free trypsin destroying 

 the erepsin. Neither pancreatic nor intestinal erepsin exists in a soluble zymogen 

 form. The peptone-splitting and fibrin-digesting powers of kept pancreatic extracts 

 vary independently, trypsin being more stable in glycerin extracts and pancreatic 

 erepsin in alcoholic. . . . 



"Pancreatic erepsin is much more readily precipitable by alcohol than trypsin [and 

 is] ... a different ferment from intestinal erepsin. . . . The action l)oth of intes- 

 tinal and of pancreatic extracts is accelerated by increasing alkalinity up to 0.4 to 1.2 

 per cent NajCOg, but the intestinal ferment — in contradistinction to the pancreatic — 

 is at the same time more and more rapidly destroyed. . . . 



"In confirmation of Cohnheim, it was found that extracts of intestinal mucous 

 membrane had little or no action on fibrin, and very little on egg-white and serum 

 proteids. Even pancreatic extracts had a much slower hydrolyzing action on native 

 proteids than upon Witte-peptone." 



