BAUMGARTNKR : SPERMATID TRANSFORMATIONS. 51 



interpret the appearances as far as possible, leaving to others, 

 or to later efforts, the complete harmonizing of this element 

 with the structures of other species. 



Before I proceed, I would add my protest against the name 

 "nebenkern," as voiced by Calkins ('95), Erlanger ('96),Meves 

 ('00) , and others. It is inapt and not at all descriptive or dis- 

 tinctive. But since we have the word, and investigators will 

 use it to mean something, I think it would be best to restrict 

 the word, as Calkins and Erlanger suggest, to the remaining 

 spindle fibers and connective fibers which go to each sperma- 

 tid and which have an important part in forming the tail mem- 

 brane. I shall retain the name for a further reason, which St. 

 George ('97) gives for first using it, "weil sie die Frage nach 

 der Herkunft dieses Gebildes offen lasst." A comparison of 

 the literature will convince any one that the origin of this ele- 

 ment is still a much-disputed question. 



1. — Nebenkern. 



There are, in Gryllus spermatids, two quite permanent and 

 prominent extra-nuclear bodies. The larger of these I shall 

 call nebenkern, because I believe it originates from the spindle 

 remains, and goes to form the tail covering. Its behavior is as 

 follows : At the beginning of the telophase the fibers which had 

 connected the centrosomes with the chromosomes bulge out 

 like barrel staves, as Henking ( '91) has described. These break 

 loose from the chromosomes and centrosomes as the clear space 

 begins to form around the chromatin mass (fig. 2) ; but they 

 are not separated injto two rings, as in Anasa and Pyrrhocoris. 

 As the dividing cell membrane is formed, the middle portions 

 of the fibers are drawn together and the so-called "mid-body ,: 

 is formed. Some of the fibers unite, producing thicker ones, as 

 seen in figs. 1,2, and 3. In the last-named figure some of the 

 central fibers seem to be still united with those of the companion 

 spermatids. 



As the daughter-cell shortens and the nucleus takes a more 

 central position these fibers unite still more, shorten, bend to- 

 gether (figs. 4, 5, and 6), and finally assume the shape shown 

 in fig. 7. I shall call it for the present the ''striated condi- 

 tion," or simply "striated nebenkern." The shape resembles 

 that of an egg with rather sharply drawn-out ends. The sur- 

 face is occupied at intervals with deeply staining lines which 



