1/6 C. M. CHILD. 



formation is much larger, and its cytoplasm is highly vacuolated 

 and more distinctly bounded from the parenchymal matrix about 

 it. These cells appear always to be connected with deeply 

 staining fibers which extend dorso-ventrally across the central 

 region of the proglottid and which I take to be dorso-ventral 

 muscle fibers since they and the cells connected with them are 

 similar to those of the muscular layers. Fig. 2, A (PL VII.), 

 shows one of these cells with a portion of its fiber. The fiber 

 passes directly through the cell-body on one side of the nucleus 

 and the cytoplasm extends visibly for a considerable distance 

 along the fiber. The evidence that these cells develop into 

 testes is very strong. Fig. 2, B (PI. VII.), represents a section 

 through nucleus and body of one of these cells in w r hich the 

 nucleus is apparently undergoing amitosis. Whether this par- 

 ticular case would have developed into a testis it is of course 

 impossible to determine. But Figs. 2, C, and 2, D(P\. VII.), rep- 

 resent characteristic cases slightly more advanced. Here sev- 

 eral nuclei are contained in a space which corresponds closely 

 with the form of the muscle cell and contains what seem to be 

 strands of the old vacuolated cytoplasm, while about some of 

 the nuclei a layer of more deeply staining cytoplasm is visible, 

 apparently in process of formation. Through the space which 

 apparently represents the region previously occupied by the body 

 of the muscle cell passes the fiber. The presence of the fiber 

 and the well marked outline of the space seem to me to consti- 

 tute very strong evidence in favor of the conclusion that each of 

 these groups of nuclei have arisen by the division of a nucleus 

 of a muscle cell. That these groups develop into testes there 

 can be no doubt. Their development can be followed from pro- 

 glottid to proglottid without the slightest difficulty, and there 

 are no other similar groups of nuclei in the parenchyma. Fig. 

 2, E (PI. VII.), shows a case in which the muscle fiber is appar- 

 ently undergoing degeneration. In all of these cases amitotic 

 division of the nuclei is taking place. The figures give only a 

 few examples of the cases observed. In a brief account of the 

 history of these cells already published additional figures are 

 given. 1 If these observations are correct, and I have, so far as 



1 Child, "The Development of Germ Cells from Differentiated Somatic Cells in 

 Moniezia." Anat. Anz., Bd. XXIX., Nos. 21 and 22, 1906. 



