550 



of the aggregations. The nuclei are apparently dividing very rapidly 

 and are much reduced in size, those near the middle of the area being 

 much smaller than those in the other regions and showing more ami- 

 toses. Since the figure represents only a small part of the mass these 

 differences are not shown. The figure is taken from near the middle, 

 however, where the nuclei are relatively small. In the outer regions 

 nuclei as large as those in the other figures occur. This part of the 

 reproductive organs differentiates into the middle region of the ducts 

 and these divisions have nothing to do with the origin of the sexual cells. 



Fig. 1. 



The figure is given merely as an example of the rapid division occurring 

 at this time. No case of mitosis has ever been observed in these 

 aggregations. 



The testes are rounded masses of cells which, as is well known, 

 are scattered through the proglottid on one side of the central par- 

 enchyma, usually designated as the dorsal side. From each testis a vas 

 efterens arises and these unite to form the vas deferens on each side. 



