1889-90.] MORPHOLOGY AND PHYSIOLOGY OF THE CELL. 255 



than when only one dose was given. He explains this on the ground 

 that the first dose has greatly increased the number of nebenkerne, and 

 thereby weakened the cells, which now respond to the second dose less 

 readily. 



Ogata also traced a relation between the disappearance of the neben- 

 kerne and the appearance of new nuclei. 



Platner's* first published views coincided to a certain extent with those 

 of Ogata. His description substantially is this: The large round 

 nucleolus of the pancreatic cell elongates, and moves towards the peri- 

 phery of the nucleus, often pushing out its membrane. The long axis of 

 the nucleolus corresponds to the radius of the nucleus. A portion of 

 the nucleus becoming constricted off, this part contains the nucleolus and 

 is separated from the main portion by the formation of a homogeneous, 

 septal wall. The nucleolus and the separated portion of the nucleus con- 

 stitute together the nebenkern, which, when the main portion of the 

 nucleus regains its usual size, sits on it like a demilune. The nebenkern 

 becomes homogeneous, separates from the nucleus and breaks up into 

 granules which are probably zymogen. These observations were made 

 on the pancreas of Anguis fragilis, and were corroborated in that of the 

 frog. 



Platner's second studyf led to somewhat different results. He used 

 for this purpose the pancreas of a number of Reptilian and Amphibian 

 forms, but he obtained the most decided results from that of the sala- 

 mander. In the latter the irregularly contoured nuclei of exhausted gland 

 cells stain deeply with safranin, so that the nuclear framework becomes 

 indistinct. Of the many or several prominences on each nucleus one 

 only remains finally. Into this the chromatin, distributed throughout the 

 nucleus, wanders, with the result that the prominence appears as a dark 

 red bud on the remaining portion of the nucleus, which now gradually 

 returns to the normal condition, namely, that in which the nucleus shows 

 an unstainable caryoplasma (Kernsaft). These buds are variously shaped, 

 large or small, round or irregular. The nuclear membrane in most of 

 the cases still covers it. Often it has vanished and the contents, still 

 colored deeply, lie as fibrillar or coiled elements, or as partially granulated 

 material, in the protoplasm of the cell. The constriction between the 

 nucleus and the bud deepens, till finally they separate, the bud now losing 

 its uniformly staining capacity. At the same time the protoplasm of 



*Uber die Entstehung der Nebenkerne und seine Beziehung zur Kerntheilung. Arch, fiir 

 Nitr. Anat. Bd., XXVI., p. 343. 



tBeitrage zur Kentniss der Zelle und ihren Theilung. Arch, fiir Mikr. Anat. Bd. XXXIII., 

 p. 180. 



