346 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



with it. The strongest argument against the contention that this cell 

 represents a stage in the early prophase, is that both nucleus and cell 

 bodies have grown very considerably while the nucleolus is of at least 

 three times the bulk of the corresponding structure in cells such as are 

 shown in Figures 120-123. Figure 130 (the nucleus only) shows the 

 practical completion of the process. The chromatin structures are now en- 

 tirely dissociated into a great number of granules, which lie at the nodes 

 of an exceedingly delicate reticulum, and the nucleus is once more filled 

 with dense and granular karyoplasm. The entire cell has increased still 

 more in size, and several metaplasmic masses are to be seen lying in the 

 cytoplasm in the neighborhood of the nuclear membrane. Of much 

 interest from a general cytologic standpoint is the mode of reappearance 

 of the karyoplasm. After all mitoses in Gonionemus this substance ap- 

 pears to be derived directly from the cytoplasm enclosed during the re- 

 formation of the nuclear membrane ; in the present case, however, if my 

 interpretation of the course of events be correct, we must suppose that 

 it is the product of the transparent nuclear sap, being thus formed as 

 the result of a series of changes directly the reverse of those which take 

 place during the early prophase. 



Growth Period. — At the close of the period of nuclear activity just 

 discussed, — the " pseudoprophase," as I have called it, — the oocyte 

 enters upon the growth period so universal in the animal egg; its nu- 

 cleus passes into the typical "resting" phase (Fig. 130), the chromatin 

 structures being resolved into their component granules. A very im- 

 portant change occurs during the early part of the growth stage. Both 

 reticulum and karyosomes almost entirely lose their affinity for nuclear 

 dyes ; and they retain this condition for a considerable period. The 

 nucleolus, no doubt the direct descendant of the nucleolus of the pseudo- 

 prophase, is at first homogeneous and stains deeply, but as it grows 

 larger one or more vacuoles appear in its substance (Fig. 130). 



In the young oocyte there is normally only one such nucleolus pres- 

 ent, but at about the time that this becomes vacuolated there appear one 

 or two other bodies, also of nucleolar nature, but of very different origin 

 and composition (Fig. 131). These are always irregular in outline, 

 somewhat spongy in structure, and stain very intensely with ordinary 

 nuclear dyes. Usually only one is found, but occasionally two or even 

 three are to be seen. They always lie at some distance from the chief 

 nucleolus, though never in contact with the nuclear membrane. When 

 first visible they are very small, hardly to be distinguished, except for 

 their stronger staining reaction, from ordinary net-knots of the reticu- 



