394 DALTON G. PAXMAN. 



granules clustered together, I believe that the larger granules 

 are the result of the union of many smaller ones. Thus, I believe 

 that the small particles of chromatin or "chromidia" are ex- 

 truded from the mother nucleus. Then these "chromidia" 

 unite here and there throughout the protoplasm to form larger 

 granules or "karyosomes" which become surrounded by a clear 

 zone. Finally the nuclear membrane is formed, producing a 

 daughter nucleus. When a number of nuclei have been formed 

 multinucleate cells are the result. Since the tissue is always a 

 cell syncytium, constrictions of the cytoplasm around a nucleus 

 finish the production of a daughter cell. Thus one mother cell 

 may produce a large number of daughter cells. 



COMPARISON WITH T^ENIA PISIFORMIS. 



In order to compare the process of cell multiplication in Dilepis 

 with that in other cestodes, Dr. Young has permitted me to 

 examine his slides of Tcenia pisiformis, and Cysticercus pisiformis. 

 Here I have identified the protoplasmic masses in both the adult 

 and the larva. These also contain nuclei in the various stages 

 of formation from chromidia to complete nuclei. The young 

 larvae show large numbers of protoplasmic masses developing 

 in the cell syncytium. In the older larvae the masses often show 

 four or five nuclei developing membranes at the same time. 



DISCUSSION. 



Cell multiplication by means of protoplasmic masses and the 

 development of nuclei from chromidia, has, so far as I am aware, 

 never been observed heretofore in Metazoa by anyone except 

 Young. He has described the process as it occurs in Cysticercus 

 pisiformis (Young, '08) and has noted it in some other cestodes 

 (Young, '10) although his interpretation varies slightly from my 

 own. I have, in the present paper given an account of it as it 

 occurs in the sub-cuticula of Dilepis scolecina. It is true that 

 chromidia have been observed in certain Metazoa, but no account 

 of their functioning in the reproduction of the cell has ever been 

 given previous to Young's paper on the " Histogenesis of Cy- 

 sticercus pisiformis." 



If cells are actually developing from protoplasmic masses in 



