302 ALLEN. [VOL. I. 



impossible to distinguish them. Later the chromatin fibers 

 lose their reticular arrangement and assemble into a varying 

 number of small spheres just within the periphery of the 

 nucleus, and at the same time the threads which support the 

 nucleolus disappear. The ground material in which the chro- 

 matin is suspended, and which up to this time has been nearly 

 transparent, now begins to react to the staining agents, and the 

 structure of the nuclei becomes obscure. If, however, methyl- 

 blue was used, this substance was only slightly affected, so that 

 this stain proved most satisfactory for the study of the various 

 phases exhibited by the retrograding nuclei, or pseudo-cells, as 

 they are sometimes called. Many of the nuclei are often 

 found in the process of division. The nucleolus lengthens 

 slightly, and finally separates into two parts. Later the entire 

 nucleus divides and part of the chromatin goes with each half. 

 Cases in which the nucleolus had divided were very numerous, 

 but very few were found in which the division was actually tak- 

 ing place. PI. II, Fig. 1 1, shows such a one, and Fig. 10 rep- 

 resents a nucleus in which there were three processes on the 

 nucleolus. No chromatin fibers were visible in either of these 

 cases. The halves thus formed often divided again, sometimes 

 before they were separated, and in some instances as many as 

 six parts can be observed. The chromatin globules vary in 

 number and size in the various parts (Fig. 12). In some of 

 the nuclei the division is less regular, and portions are often 

 found in the process of being absorbed into the protoplasm of 

 the egg. Fig. 15 represents a nucleus in which the parts 

 formed by the first division were of very unequal size. In the 

 smaller the nucleolus has again divided, but the larger part has 

 been partially absorbed. Often several of these nuclei are 

 found in a single vacuole. Fig. 9 shows one in which there 

 were seven in various stages of disintegration, but usually not 

 so many are found. Doflein believes that they are carried 

 into the vacuoles by currents in the protoplasm. All this goes 

 to strengthen the opinion of Doflein that the absorbed nuclei 

 take the place of the yolk-granules, which are wanting in this 

 species, and that they are gradually broken down to serve as 

 food for the developing egg. They persist through the entire 



