360 H. HONDA. 



probable explanation seems to lie in the imperfect mitosis. She 

 detected no evidence of degeneracy among the young spermatids. 



VI. SUMMARY. 



1. In Stomaphis yanois the smaller secondary spermatocytes 

 divide, and develop to some extent, but retrogress to spherical 

 cells. 



2. In Neothoniasia populicola and Macrosiphum ambrosia, 

 cases of division of the smaller secondary spermatocytes were 

 found, but no developing smaller spermatids were observed. 



3. In Neothoniasia populicola and Macrosiphinn ambrosia 

 spherical cells like tho<se in Stomaphis yanois were found in the 

 cysts containing spermatozoa. These were identified as retro- 

 gressed larger spermatids. 



LITERATURE. 



von Baehr, W. B. 



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 Meves, F. 



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