90 NICHOLS— SPERMATOGENESIS ONISCUS ASELLUS LINN. [April 4, 



of the Dytiscid, Coly?nbetes striatus. These adhere together after 

 having reached maturity. Their structure and mode of origin is, 

 therefore, not the same as that of the bundles of Oniscus. The 

 term "compound spermatozoon" has been suggested to me, but 

 the word spermatozoon might carry with it certain implications 

 with regard to behavior in fertilization. I prefer, therefore, to use 

 the term sperm colony, at least until a better one offers itself. 

 Gilson uses this term also, although not so generally as the word 

 '* spermatophore." 



The number of nuclei entering a colony varies within rather 

 wide limits. I have counted as few as six and also as many as four- 

 teen. In cross sections stained with saffranin and malachite green, 

 they are seen as red bodies surrounding a central mass of green 

 dots, the sections of the cytoplasmic fibrils (Fig. 80). The red 

 dots diminish in size toward the anterior end of the bundle, and 

 at one point can be seen merging directly into delicate green 

 threads (Fig. 80^). At the extreme anterior end of the bundle the 

 delicate green threads alone will be cut (Fig. %oa). It might be 

 supposed that the bundle of cytoplasmic fibres previously described 

 are the tails of the spermatozoa. If they are really the tails of the 

 spermatozoa, one would expect to find them at some place con- 

 nected with the nuclei, or with the delicate fibres which can be 

 demonstrated to be continuous with the nuclei. A comparison of 

 sections obtained at different levels seems to leave but two alterna- 

 tives : either the long bundle of cytoplasmic fibres stops abruptly 

 before the anterior end of the colony is reached, or the connection 

 is of so tenuous a character as to escape observation. In structures 

 of such minuteness the latter might easily be the case. 



A point bearing on this matter, and therefore of interest to deter- 

 mine, is the number of cytoplasmic fibres as compared with the 

 number of nuclei. Attempts to determine this might be made in 

 two ways. The mature sperm colonies taken from the vas and 

 teased apart might be examined and an attempt made to count the 

 fibres at the frayed end of the bundle, or one might try to count 

 the number as seen in cross sections. By either method it is difii- 

 cult to be sure of an accurate count, for in the frayed ends of col- 

 onies one or more of the fibres may adhere together. In cross 

 sections the fibres appear as minute dots, as a rule, closely crowded 

 together. Occasionally they may be more loosely distributed. 

 Fig. Z\b represents a cell of this sort in which the num.ber of cyto- 



