382 R. R. BENSLEY 



sort is very confusing, but easy enough to differentiate if the gran- 

 ules of the islet and acinus cells are sufficiently well stained. 



The second statement of Laguesse which would carry convic- 

 tion if sufficiently well established is to the effect that, on the sur- 

 face of the islets in the human pancreas, he finds remains of acini, 

 which have no connection with the duct system, and which are 

 included under the same basement membrane as islet cells. The 

 last half of this statement, is of course merely a restatement of the 

 fact of continuity, for continuity involves continuity under the 

 same basement membrane. The acini in question, according to 

 Laguesse, form cap-like masses over the ends of columns of islet 

 tissue which terminate on the surface of the islet. In discussing 

 this condition he quotes Dewitt ('07) as having found a similar 

 condition in the rabbit, which she explained by assuming that the 

 embryonic connections of the islets and acini had persisted. La- 

 guesse criticises this conclusion on the ground that experiments 

 with duct ligation showed that acini cut off from their duct 

 connection, rapidly lost their zymogen. On examining Dewitt's 

 article, however, I find that Laguesse has misunderstood Dewitt's 

 description, for her intention is to describe continuity between 

 islet and acinus tissue without admitting that the latter is dis- 

 connected from the duct. Laguesse, in this discussion has fur- 

 nished an argument against his own conclusion that the acini 

 observed by him on the periphery of the islet are separated from 

 their duct, for if this were true, according to his own statement, 

 zymogen should not be present in the acinus cells. It is well to 

 remember also in this connection that it is frequently impossible 

 to see the lumen even in acini far removed from the islets, be- 

 cause the cells fall together in fixation and the lumen is thus oblit- 

 erated. 



Laguesse's figures on plates 1 and 2 ('10) giving a complete 

 series through an islet and the surrounding tissue, I have examined 

 carefully, and while in some places single sections seem to show 

 isolated groups of acinus cells in contact with islet cells and de- 

 tached from the neighboring acinus tissue, following the series 

 through shows that every acinus cell is connected with the duct 

 by other acinus cells or by centroacinous cells. 



