THE SPERMATOGENESIS OF PANDARUS SINUATUS 



SAY. 



J. F. McCLENDON. 



The spermatogenesis of the parasitic copepods of the Woods 

 Hole region was included as a preliminary note in a previous 

 paper of mine (McClendon, '06), L&margus muricatus Kroyer 

 being taken as an example. The spermatogenesis of these forms 

 is more nearly identical than the oogenesis. In fact, the great- 

 est difference is in the number and size of the cells in the testes. 

 The advantage in studying Lcemargus was the greater size and 

 greater number of cells in the testes, but the difficulty of obtain- 

 ing living material of this genus led to the substitution of 

 Pandarus. 



The material for the present paper was procured at Woods 

 Hole last summer. The testes with more or less adjacent tissue 

 were removed and fixed in Flemming's stronger fluid. Paraffine 

 sections, 3 to 7 microns in thickness, were cut, and stained in 

 various ways. Iron haematoxylin, Delafield's haematoxylin, saf- 

 franin, orange G, and various combinations were found valuable. 

 Not a great deal of attention was paid to the exact form in which 

 the cytoplasm and nuclear sap was coagulated by the fixation, 

 but attention was directed chiefly to the chromatin of the nucleus 

 and to those remarkable bodies described in the previous paper 

 under the name of nutritive spheres. 



The spermatogonia (Fig. 1) are nearly isodiametrical cells with 

 large spheroid nuclei. Each nucleus contains during the rest 

 stage two or more nucleoli (plasmosomes) and a reticulum in 

 which chromatin granules are imbedded. During mitosis sixteen 

 chromosomes are formed and divided (Figs. 2 and 3), one half 

 of each chromosome going to each of the two daughter cells. 



The primary spermatocytes when first formed (Fig. 4) are 

 similar to the spermatogonia except for size. The nucleoli never 

 grow to the size they reach in the spermatogonia, probably 

 because the prophase of mitosis begins early in the growth of the 

 cell and the nucleoli begin to dissolve before they have had time 



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