35O H. HONDA. 



sometimes show a division figure, which subsequently fades away, 

 but I have never seen a case of this kind." 



In Macrosiphum ambrosia: and Ncothomasia popnlicola I have 

 observed the late telophase of the smaller secondary spermato- 

 cytes. In Stomaphis yanois, moreover, I have found that the 

 smaller secondary spermatocytes divide and form equal-sized 

 spermatids which are much smaller than the larger spermatids. 

 These smaller spermatids develop and reach the sustentacular 

 cells with the developed larger spermatids ; they, however, fail to 

 attach to the sustentacular cells. Thus their development ceases ; 

 they, therefore, do not fully transform into spermatozoa, but 

 retrogress and form spherical cells, which attach themselves to 

 the epithelium of the cysts of the testes. A further account of 

 this will appear in the following pages. 



The work on the spermatogenesis of Stomaphis yanois was 

 done in the Tokyo Higher Normal College, and the work on the 

 other aphids has been done in the University of Chciago. The 

 writer's thanks are due to Prof. F. R. Lillie and Prof. S. Yama- 

 nouchi, who gave him many suggestions and much help. The 

 writer also wishes to thank Prof. A. Oka and Prof. U. Takakura 

 for their kindness during his stay in Tokyo. For the identifica- 

 tion of the aphids the writer is indebted to Dr. A. L. Quaintance 

 and Dr. A. C. Baker. 



II. METHODS. 



Both the males and parthenogenetic females were fixed in 

 either strong Flemming's, Zenker's or a mixture of absolute alco- 

 hol one part, acetic acid one part, and saturated aqueous solution 

 of corrosive sublimate two parts. Sections were cut 3, 5 and 10 

 micra in thickness ; most of them, however, were cut 5 micra 

 thick. They were stained with Heidenhain's iron-hematoxylin 

 followed by eosin or borax carmin. 



III. STOMAPHIS YANOIS. 

 i. Primary Spcrmatocytc. 



Figs, i and 2 show the primary spermatocyte prophase. In 

 Fig. i, one of the chromosomes is formed, and in Fig. 2, the proc- 



