STUDIES ON THE PANCREAS OF THE GUINEA PIG 381 



ever, whither this conception of cell life would lead Laguesse if 

 he should attempt to apply it to the case of the gastric glands with 

 their intermixture of chief and parietal cells, or to the intestinal 

 glands, or to the nervous system. However, Laguesse's two alter- 

 natives do not exhaust the possibilities of the case, as he supposes, 

 for it is possible if the cells are not really persistent throughout 

 life, which we do not know, that both acinus cells and islet cells 

 of such a mixed group, after a certain period of functioning, dis- 

 appear and are replaced by new elements which grow out from 

 the relatively undifferentiated but highly potent epithelium of the 

 duct. This possibility is well illustrated by the observations of 

 Gontier de la Roche ('02) who showed that after the disappearance 

 of the acinus tissue, resulting from occlusion of the pancreatic duct, 

 both new acini and new islets were formed from the duct system. 

 In his latest paper Laguesse ('10) has described two conditions 

 which are more significant than the foregoing, and which, if con- 

 firmed, under proper precautions would go a long way to establish 

 his claim that acini may be converted into islets, though he would 

 still be far from proving that this process is of common occurrence 

 in the pancreas. In his article on the relation of islets to acini 

 in man he describes a cell which is interposed between islet cells 

 on the one side and acinus cells on the other and which partakes 

 of the structure and staining reactions of both. This cell is from 

 a preparation fixed in acetic sublimate and stained in safranin 

 picric acid and naphthol black. The cell shows on the side next 

 the islet faintly indicated islet characters, and on the other well 

 defined acinus characters. This if a little more definite, is the 

 kind of transition which I have sought with great care in my pre- 

 parations, but without success, for when I thought at first that 

 I had found such a cell, I have found invariably, on closer study, 

 that it was simply a case of overlapping of the two cells. This, I 

 suspect, is also the case in Laguesse's preparation. For although 

 he is careful to say that no islet cells overlie this cell in the neigh- 

 boring sections, yet the appearance would be well explained if 

 one supposed that the adjacent islet and acinus cells had an oblique 

 surface of contact so that a thin sector of the islet cell was included 

 in the same field of view as the acinus cell. Overlapping of this 



