8 The Ohio Naturalist. [Vol. XIII, No. 1, 



cases there is only one. There is no difficulty in distinguishing 

 the nucleoli from chromatin material since the safranin used in 

 the combination stain gives the nucleoli a peculiar reddish tinge 

 while chromatin material stains nearly black The nucleolus is 

 in the middle of the nucleus, sometimes a little to one side; and 

 on the periphery of the nucleus is the network and chromatin 

 granules spoken of above. A little later the nucleus begins to 

 swell very considerably, and gradually the network is loosened 

 in one place or another from the nuclear wall. At this time the 

 nucleolus is still in the middle of the nucleus. As the process 

 continues the nucleus becomes larger and more of the threads 

 becomes loosened from the wall (Figs. G. 7. 8). 



At this stage the synizesis begins, the spirem massing together 

 into an irregular lump which may or may not enclose the nucleolus. 

 In some cases the nucleolus may be entirely separate from the 

 synizetic knot. No division of the granules or longitudinal 

 split of the spirem was observed. There is a well defined thread 

 now present and in some cases loops of the thread could be seen 

 sticking out from the opaque knot (Figs. 9 and 11). In other 

 places little apparently free ends of the thread projected from the 

 mass. On these threads defiinite chromatin graniiles were 

 plainly visible and could easily be counted in any free loop. 

 Whether the free ends represented natural breaks in the spirem 

 or injuries caused by the contraction or the cutting, corild of 

 course, not be determined. But the appearance of the spirem 

 before and after the synizesis indicates that the spirem is con- 

 tinuous. The contracted chromatin mass was sometimes formed 

 to one side of the nuclear cavity and sometimes in the middle 

 (Figs. 9, 17). Sometimes it extended across the nucleus. There 

 were various stages of contraction from the loosely coiled mass in 

 which the threads were clearly visible (Fig. 11) to the tightly 

 contracted mass in which no structure, whatsoever, could be made 

 out. During older stages of the synizesis the knot is very much 

 looser and the thread is much more complete and is thicker with 

 the granules of a more unifonn size. There is no question but 

 that there has been a contraction of the chormatin, the mass 

 occupying a much smaller area than before, while the nuclear 

 cavity is much larger. Whether some of the enlargement of the 

 nuclear cavity was due to plasmolizing reagents or entirely due 

 to a normal growth could not be determined since there is consider- 

 able difference in the size of various nuclei of apparently the same 

 stage of develoiOTient. 



Immediately after the synizesis the threads are delicate and 

 contain numerous small granules. It is exceedingly difficult to 

 follow the thread through all its convolution but in some cases it 

 could be traced for quite a long distance (Figs, 12, 13, 14). There 

 is generally one nucleolus at this stage but in some cases two are 



