STUDIES ON THE RELATION BETWEEN AMITOSIS 



AND MITOSIS. 



II. DEVELOPMENT OF THE TESTES AND SPERMATOGENESIS IN 



MONIEZIA. 

 C. M. CHILD. 



The material for this study was obtained from the same spe- 

 cies, vis., Moniezia expansa and Moniezia pianissimo,, as that of 

 the first paper of this series * and most of it, in fact from the 

 same chains. The methods of fixation, observation and record 

 are the same as those already described in that paper. Various 

 details in the spermatogenesis are only briefly considered, since 

 they are not directly connected with the chief purpose of the 

 paper. 



I. The Formation of the Te&tes. 



The testes develop from cells of the parenchyma which do not 

 differ visibly from other cells of the same region. They appear in 

 the dorsal region of the central parenchyma. Before their appear- 

 ance two kinds of cells are visible in the parenchyma : one of 

 these is smaller and surrounded by more or less cytoplasm ap- 

 parently without definite boundary and usually elongated in the 

 dorso-ventral direction, with one or more fibrillar extensions at 

 each end. Figs. I, A-D (PI. VII.), show parenchymal cells of this 

 kind in the earliest stages of testis formation. Amitotic division 

 of the nucleus is occurring in each case. Fig. I, A, shows a case 

 in which the two parts of the dividing nucleus stain differently 

 Fig. i, C, a case of the endogenous form of nuclear division 

 which was described in the preceding paper, while Figs, i, B, 

 and i, D, show late stages in division, the one by constriction, 

 the other by formation of a nuclear plate. For a description of 

 these and other forms and stages of amitosis in Moniezia the 

 reader is referred to the preceding paper of this series. 



The other form of cell existing in the parenchyma before testis 



1 Child, " Studies on the Relation between Amitosis and Mitosis I. Development 

 of the Ovary and Oogenesis in Moniezia," BIOL. BULL., Vol. XII., No. 2, 1907. 



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