STUDIES ON THE PANCREAS OF THE GUINEA PIG 337 



making it unnecessary to continue this objectionable form of 

 experimentation. The time of withdrawal of food varied from 

 five to seven days, water being supplied to the animals for the 

 whole period. 



There is clearly no indication in these cases of an increase in 

 the number of islets as the result of the period of inanition. On 

 the contrary, one might be tempted to conclude that the number 

 had actually been reduced but for the fact that a reference to 

 table 1 showing the islet contents in normal resting pancreases 

 shows that large numbers of the normal animals have an islet 

 content as low as, or even lower than that shown in these experi- 

 ments. 



4. Effect of inanition on the number of islets in the pancreas of 



the dog 



In order to meet the possible criticism of the results in the 

 guinea pig, that owing to its herbivorous habit the initial content 

 of islets was large, similar experiments were made in dogs. Here 

 again it was impossible to repeat exactly the experiment of Vin- 

 cent and Thompson ('07) because they give no indication in their 

 paper of the duration of the experiment, simply saying that "the 

 difference between a section of a normal resting pancreas of a dog 

 and one of a pancreas from a dog which has undergone inanition 

 for several days is so striking as to render it almost incredible that 

 observers could have disagreed on this point." Attempts to 

 obtain convincing results by the examination of sections from cor- 

 responding portions of the pancreas of normal and inanition dogs 

 having been unsuccessful in yielding constant differences, it 

 seemed possible that the failure might be due to the comparison 

 of animals which, owing to difference of age or of mode of life, 

 were really not comparable. Accordingly, I made the effort 

 to secure for this purpose litters of new born pups, rear them in 

 the laboratory, and use them for this experiment. So far I 

 have not had litters of sufficient numbers at my disposal to 

 establish adequate controls among the members of the same 

 litter, and have had in series 1 which follows to use for controls 



