THE RELATION BETWEEN AMITOSIS AND MITOSIS. I Op 



but in different proglottids. The chain in which mitosis was 

 almost never seen in the ovarian development produced appar- 

 ently as many eggs as others and these developed in the normal 

 manner in the uterus. 



VI. THE GROWTH PERIOD, " SYNAPSIS " AND YOLK FORMATION. 



Although the later stages in the formation of the ova are not 

 concerned directly with amitosis a brief description of these stages 

 is added in order to demonstrate that nuclei which have passed 

 through a long series of amitoses are quite capable of exhibiting 

 the characteristic phenomena of typical germ cells. These 

 stages in the development of the ova also appear to be identical 

 in both species. All the figures except 22, 23 and 30, AD, are 

 from M. cxpansa. 



The oogonia at the end of the period of division are seen in 

 Fig. 1 8. There is little difference in appearance between them 

 and the dividing cells during ovarian development. The amount 

 of cytoplasm is perhaps slightly greater, but this difference is not 

 marked. 



But now the nuclei undergo a sudden and remarkable change. 

 The only deeply staining portions of the nucleus up to this time 

 have been the nucleolus and frequently a few other granules 

 (Fig. 1 8). Now the nucleus develops rapidly a large amount of 

 chromatin. The earliest observed stages in this development are 

 shown in Fig. 19, Aig, C. This change in the nuclear sub- 

 stance is accompanied by a great increase in size of both nucleus 

 and cytoplasm. The chromatin soon shows itself in the form of 

 a typical spireme (Figs. 20, A-2O, E, 23, A, 23, B] which is com- 

 monly massed at one side of the nucleus (Figs. 20 A, 20, C, 2O, 

 E, 23, A, 23, E] and in most cases is visibly connected with the 

 nucleolus. So far as can be determined the spireme does not 

 appear to be formed from the substance of the nucleolus, since 

 the latter increases in size like the other elements of the cell. 

 This is clearly a typical case of what is commonly known as 

 synapsis. 



'The appearance of these stages varies considerably with the 

 degree of extraction of the stain. If extraction is carried farther 

 than in Fig. 20 only small portions of the spireme or often only 



