74 KANSAS UNIVERSITY QUARTERLY. 



seems to me that any results derived from a study of this object should 

 not be accepted unless well supported by similar appearances in other 

 animals. 



The other possilnlities are such as have found expression from in- 

 vestigations upon insect material and that of other Arthropods. Wil- 

 cox, from a study of the genera Melanoplus and Cicada, becomes an 

 advocate of the formation of the tetrads by the second possibility, i. e., 

 by repeated cross-divisions. As in thecase of Ascaris, there is little 

 to support this view in the appearances found in other objects. 



The remaining explanation, according to which the tetrad is formed 

 by one longitudinal and one cross-division, is advocated by Henking, 

 vom Rath, and Hacker, and more recently by Paulmier and Mont- 

 gomery. These authors are all in agreement upon the question of 

 the two forms of division, but are in dispute as to whether the longi- 

 tudinal or the cross-division is first to occur. 



It is the purpose of the jjresent paper to contribute to the existing 

 observations upon these disputed subjects and to offer some explana- 

 tions suggested by the study of Orthopteran spermatogene.sis, as mani- 

 fested in the Acridid?^. The principal object of study has been 

 Hippiscus plujcnicopteriis, but the facts observed in this form have 

 been verified by examination of numerous other genera, so that what 

 is here given may, I think, be considered typical for the family. 



I. — MATERIALS AND METHODS. 



The first specimens of Hlppiscus were captured early in the spring. 

 These were either adults, or nymphs in the final period of their trans- 

 formation, which had wintered over in this stage. The condition of 

 the testes in the two forms was essentially the same. In the follicles 

 of the first individuals taken most of the cells were in the prophases 

 of the first spermatocyte division, and had evidently endured the 

 winter in this condition, for, after a few days of warm weather, large 

 numbers of the cells were observed passing through the later stages 

 of division. The continuance of the spireme during the hibernation 

 of the animal was further confirmed by observations upon nymphs of 

 the second moult taken in the fall. Here a great portion of each fol- 

 licle was found to be filled with cells established in the spireme stage. 



I cannot refrain from calling attention to the very excellent char- 

 acter of the material conveniently offered by this widely distributed 

 insect for the study of spermatogenesis. The cells are even larger 

 than those of the Amphi'uina testis and are much more favorable for 

 observation on account of the smaller size of the organ and lesser 

 number of nuclear elements. 



For fixing the tissue, a variety of agents was employed, but all 

 were finally discarded in favor of the osmic acid mixtures of Hermann 



