1889-90.] MORPHOLOGY AND PHYSIOLOGY OF THE CELL. 269 



work has been of great service in calling special attention to structures, 

 the further study of which may definitely establish a new function for the 

 pancreas in cold-blooded animals, viz., a protective one against the 

 Haematozoic parasites. 



In connection with these remarks on Ogata's views, I may mention 

 that I have frequently observed in some sections of the pancreas of 

 Diemyctylus examples of karyokinesis and that in the cells in this con- 

 dition there were neither nebenkerne, protoplasmic masses, nor plasmoso- 

 mata. Steinhaus gives an illustration of" a pancreatic cell exhibiting 

 karyokinesis in which, apparently also, nebenkerne (parasitic) are present. 

 I have also frequently observed cell and nuclear division in the pancrea- 

 tic cells of the young Amblystomata and it was apparent that the nuclear 

 division might go on with the cell more or less filled with zymogen 

 granules. 



4. Zymogenesis. 



It has been known from the researches of Haidenhain and others that 

 changes in the shape and staining power of the nucleus accompany the 

 change from the resting to the active phase of the secreting cell. What 

 the relations are which these changes bear to one another, were not divined, 

 but it was generally supposed that they were the results of increased or 

 decreased nutrition. The observations of Plainer and Steinhaus embrace 

 one aspect of these changes i.e., the staining power of the nucleus, and it 

 is to this that I propose to devote this section. 



A summary of Platner's views as to the changes in the staining power 

 of the nucleus of the pancreatic cell has been given above in the histori- 

 cal sketch of the literature on the pancreatic nebenkerne. Steinhaus'* 

 observations, bearing more directly on the staining power, are of greater 

 interest to us and may be abstracted as follows : 



The exhausted gland cells are small, indistinctly contoured, and defi- 

 cient in protoplasm and their arrangement in the form of alveoli is lost. 

 Their nuclei which are angular and crenated are, when a double stain of 

 haematoxylin and safranin is employed, colored red, and their nucleoli are 

 safranophilous. When the active phase of the cells begins, the cytoplasm 

 increases, the contour of the cell becomes distinct, the arrangement in 

 alveoli with central lumen is attained, while the form of the cell becomes 

 bluntly conical. At the same time the nucleus becomes oval and stains 

 readily with haematoxylin. This dye stains one sort of nucleoli, the kary- 

 osomata, while the safranin colors the other and larger kind, the plasmo- 



* op. cit. p. 377. 



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