460 THEOPHILUS S. PAINTER 



figures 12 and 14. The spindle which results (fig. 24) appears 

 normal except for the large number of chromosomes lying in 

 the equatorial plate. I have not been able to count the exact 

 number in the spindle, but corresponding stages in monaster 

 eggs show 72 chromosomes (text fig. 9). In telophase stages 

 the asters become extremely large, but I have found no sections 

 through eggs just at the period when cleavage was taking place. 



The triasters and tetrasters found in section and observed 

 in the living eggs at this period, are to be derived, I believe, 

 from these monaster eggs in which the centrioles divided early. 

 They do not differ in section from similar eggs produced by 

 dispermy. 



Those monaster eggs in which the monaster persists in the 

 second division cycle show considerable variation in appearance. 

 In figure E x a rather common form is shown. The swollen 

 ectoplasmic layer, and the irregular shape of the egg are rem- 

 inants of the protoplasmic movement of the first division cycle. 

 We see here the centrosphere surrounded by very short astral 

 rays to which the chromosomes are attached. Figure 22 shows 

 a later stage when the chromosome vesicles are beginning to 

 fuse. 



In figure Fi to F 7 we have drawings of other types of monaster 

 eggs. Figure Fi is a later phase of the first monaster cycle. 

 Figure F 2 shows a typical form of the second monaster. A clear 

 defined centrosphere is not to be seen. Instead, the aster rays 

 arise from a ill-defined area, and the chromosomes, instead of 

 lying on one side of the aster, are here scattered all around the 

 aster. Careful counts (fig. G) show about 72 chromosomes in 

 the egg. Not infrequently, instead of one general center, 

 there are four ill-defined centers from which the aster fibers 

 arise. Figures F 4 to F 7 show sections through later stages. 

 The irregular form of the eggs is due to the extraordinary move- 

 ment of the protoplasm which follows the formation of the 

 nuclear vesicles in the division cycle. 



In later stages we may find the persistence of a single aster 

 but more usually a great number are present as is shown in 

 figure 23. 



