58 KANSAS UNIVERSITY SCIENCE BULLETIN. 



and then grows out into the axial filament. The centroeome moves half way 

 around the nucleus and lies between the latter and the nebenkern. Later the 

 centrosome becomes the middle piece. 



This description does not give much detail nor do the draw- 

 ings show the stages clearly. As far as given, the formation 

 of the nebenkern is the same as in Gryllus ; but in Gryllus the 

 axial filament is not formed from the nebenkern, as can be 

 plainly seen from fig. 17. 



Erlanger ('96), in a short paper, discusses the use of the term "nebenkern," 

 and suggests limiting it as is done in this paper. He opposes St. George's opinion, 

 that the nebenkern comes from the cytomicrosomes. In Blatta the cytomicro- 

 somes are preserved during the whole process of mitosis, and have no connection 

 with the spindle fibers, but during the telophase they collect in reduced numbers 

 around the daughter nuclei. 



In 1897 he called the collection of granules around the centrosome, the centro- 

 deutoplasm. He considers them to be identical with St. George's cytomicrosomes 

 and the archoplasm ( or attraction sphere ) of other writers. In order to harmonize 

 results, he suggests that, since the centrosome sometimes wanders around the 

 nucleus, the centrodeutoplasm (or sphere) may unite with the spindle remains 

 in some cases to form one body, as shown by the descriptions of Henking, 

 Henneguy, Meves, and others. He later ('97, 2) describes the so called "sphere," 

 and distinguishes between it and the true nebenkern. 



I would strongly commend his excellent- discussion of litera- 

 ture and his careful comparison of the results of investigators. 

 He has shown clearly that the nebenkern comes from the spin- 

 dle remains. 



Calkins ('96) finds that the nebenkern comes from the spin- 

 dle fibers and is useless in the cell. But Lumbricus is peculiar 

 in having the nebenkern simply disintegrate, for, in many 

 cases, he admits that the nebenkern has an important func- 

 tion. I do not have access to Henneguy 's or Bolles-Lee's 

 or Toyama's works, yet I should judge from Erlanger's and 

 Meves's criticism that all of these have the nebenkern originate 

 from the spindle remains, and Henneguy describes it as having 

 a "fibrillar appearance," and Bolles-Lee as "fibrillar struc- 

 ture." Accordingly, I think that each of these has discovered 

 the correct origin of the structure, and I do not doubt that there 

 is, at least in the first two, a more or less direct change from 

 the spindle remains to the nebenkern. 



Paulmier ('99) finds that in Anasa the nebenkern comes from the yolk mass 

 and remains of the spindle fibers. A part of this mass separates off, while the 

 whole is still in a confused condition, and forms the acrosome. The nebenkern 

 forms the tail sheath, while the acrosome forms the point to the head. 



A comparison of Paulmier's fig. 42 with my fig. 4 suggests 



