REGULATION OF THE PANCREATIC SECRETION. 235 



he was killed and the pancreas removed immediately, an 

 extract made of it and its power of acting upon milk-sugar 

 (lactase content) determined. The extract was found to 

 have practically no effect upon milk-sugar, indicating, there- 

 fore, that it contained little or no ferment capable of acting 

 on lactose. A second, also adult dog received for 15 days a 

 diet similar to that given the first dog, only 30 gms. of milk- 

 sugar were added to the daily food ration. When at the 

 end of this time the dog was killed, the pancreas removed 

 and treated as that of the first dog, it was found that the 

 pancreatic extract split milk-sugar most energetically into jgalac- 

 tose and dextrose, 43 percent of thelidded lactose being 

 split within twenty-four hours. It is self-evident, therefore, 

 that under the influence of milk-sugar feeding the pancreas 

 can develop a ferment (lactase) which has the power of split- 

 ting milk-sugar and which is entirely absent (or present in 

 only very small amounts) in the pancreas of an adult dog 

 not so fed. 



The percent of sugar split aS given above is by no means 

 the highest that WEINLAND ever attained. In three other 

 experiments in which the dogs were fed ordinary milk instead 

 of pure milk-sugar, the pancreatic extracts were able to split 

 respectively 54 percent, 73 percent, and 75 percent of the 

 lactose added to them. When it is pointed out that the 

 pancreas obtained from dogs of a corresponding age, but not 

 fed on milk-sugar, possess practically no milk-sugar-splitting 

 activity it is self-apparent how striking is this " adaptation'! 

 of the pancreas to the character of the diet. 



It is of physiological interest that the quantitative variation 

 in the amount of lactase found not only in the pancreas but 

 also in the small intestine is intimately connected with the 

 age of the individual, or, as we can say now, with those 

 periods of life in which milk-sugar furnishes a part of the 

 food consumed by the animal. Apparently all sucklings 

 (including the new-born child) have lactase present in the 

 pancreatic juice and the intestinal juice. This has been 



