STUDIES ON THE PANCREAS OF THE GUINEA PIG 379 



thus possible by a suitable choice of fixing agent and stain to re- 

 tain the Mankowski granules, and to eliminate in turn the A 

 granules and the B granules, and even the zymogen granules. 



Accordingly, we must conclude, that Mankowski's identification 

 of these granules as islet granules was based on a superficial resem- 

 blance to one another of two things which are really not similar. 



Laguesse ('06-08) identified the cells of the A type as cells of 

 transition between the acinus cells and the B cells which he re- 

 garded as the definitive islet type. He says: "Nous ajouterons 

 encore. . . . que nous y voyons un stade de transition entre 

 les cellules principales d'acini et les cellules d'ilot en periode d'etat. 

 Chez le cobaye notamment, nous ne recontrons qu'un petit 

 nombre de ces cellules de deuxieme variete, et nous les trouvons 

 precisement aux points de continuite avec les acini, ou meme 

 isolees dans les acini voisins." 



I have already discussed this conclusion and have shown that 

 it is based on incorrect notions of the distribution of the A cells, 

 which do not occur exclusively on the surface of the islet, and do 

 occur in large numbers in islets which have no connection with 

 acinus tissue. The A cells which Laguesse supposed to occur in 

 the neighboring acini are probably acinus cells undergoing the 

 Mankowski degeneration, for in the guinea pig the A cells only 

 occur in large numbers in the acini in the first week of life. 



The arguments advanced by Laguesse in favor of the theory of 

 transformation, I have examined with great care in his voluminous 

 writings on this topic, and with the exceptions which I shall dis- 

 cuss later, they seem to me to prove nothing more than continuity 

 of islet tissue with acini and with ducts. His latest paper on the 

 conditions in the human pancreas is largely devoted to this proof 

 of continuity, and I have already indicated my full agreement 

 with him in this respect. But does continuity necessarily mean 

 that the islets are growing at the expense of the acini, or the acini 

 at the expense of the islets? I think not, for if we admit this con- 

 tention for the pancreas we must also admit it for other tissues, 

 and conclude, for example, that the demilunes of the mucous 

 glands are derived from mucous cells or vice versa, and that the 

 parietal cells are derived from the chief cells of the gastric glands. 



THE AMERICAN JOUHNAI. OF ANATOMY, VOI.. 12, NO. 3 



