SPERMATOGENESIS OF APHIDS ; THE FATE OF THE 

 SMALLER SECONDARY SPERMATOCYTE. 



H. HONDA. 



CONTENTS. 



I. Introduction ^49 



II. Method 35 o 



III. Stomaphis yanois 350 



1 . Primary Spermatocyte 350 



2. Larger Secondary Spermatocyte 351 



3. Smaller Secondary Spermatocyte 352 



4. Smaller spermatid 353 



IV. Neothomasia populicola and Macrosiphum ambrosia: 356 



V. Review 358 



VI. Summary 360 



I. INTRODUCTION. 



It has been shown by Morgan and von Baehr that in aphids 

 the primary Spermatocyte divides unequally producing larger 

 and smaller secondary spermatocytes. The larger secondary 

 Spermatocyte undergoes a second maturation division, and pro- 

 duces two equal-sized spermatids which transform into func- 

 tional spermatozoa. The smaller secondary Spermatocyte, which 

 has received fewer chromosomes is said to degenerate. Only two 

 similar spermatozoa, consequently, are formed from a primary 

 spermatocyte. 



Von Baehr (1909 and 1912) states that he very rarely observed 

 the development of the smaller secondary spermatocyte to the 

 prophase of the second maturation division, but that it does not 

 divide. Stevens (1909) says that in a preparation which has 

 unfortunately been lost, the anaphase of the smaller secondary 

 spermatocyte was seen, and that such stage may also be distin- 

 guished among the degenerating spermatocytes. Morgan (1915) 

 states : " The small cell is left with two chromosomes and a small 

 amount of cytoplasm. It never divides again, and later degen- 

 erates. Stevens was inclined to think that the small cell may 



349 



