STUDIES ON THE PANCREAS OF THE GUINEA PIG 323 



by the facts. In the first place he assumes that pieces taken from 

 the corresponding portions of the pancreas of different individu- 

 als are in the same degree representative of the total contents of 

 islets in the pancreas. Table 2 shows that this is not the case for 

 the guinea pig. In the second place he assumes that such pieces, 

 carefully selected, are to the same degree representative of the 

 portion of the pancreas from which they are taken. Table 3 

 shows that this may or may not be true. Finally, a very large series 

 of control normal animals must be taken to insure that the worker 

 has an adequate appreciation of the range of individual variation. 

 Another factor which vitiates the result of the section method is 

 the fact that the islets are rarely located near the surface of the 

 lobules, so that a section through the surface layers of the lobule 

 may show few islets and small islets when the lobule in reality 

 contains many and large ones. 



In view of these considerations it seemed desirable to test by 

 the method of total counts the claim of Statkewitsch ('94), Dale 

 ('05), Laguesse ('10) and Vincent and Thompson ('07) that the 

 number of islets and their size is increased by inanition, and that 

 of Dale ('05) and of Vincent and Thompson ('07) that a similar 

 increase is produced by secretin stimulation. It is extremely 

 important that a correct answer should be obtained to these ques- 

 tions, not only because they affect our views concerning the inter- 

 relation of the islets and acini in the pancreas, but also because 

 they affect all conclusions as to functional differentiation which 

 are based on anatomical grounds. For, if it can be shown that, 

 as a result of a few hours stimulation with secretin, a pancreas 

 transforms a great quantity, or indeed any, of its acinus tissue into 

 islet tissue, the islet tissue thereby loses all significance it may 

 have as a special organ of internal secretion, and similarly, doubt 

 is thrown on all conclusions as to difference of function, based on 

 anatomical facts of the same order as the differences between the 

 islet cells and acinus cells. It should be pointed out here that 

 the balance theory of Laguesse does not carry the same impli- 

 cations, for it presupposes a special function for the islets of 

 Langerhans and agrees with the ideas of Dale, Vincent and 

 Thompson only to the extent that it assumes that the two tissues 



