696 C. E. McCLUNG 



spermatocyte homologous chromosomes divide longitudinally 

 and so undergo an equation division. 



Randolph ('08) gives an outline account of the spermatogenesis 

 in the earwig, Anisolabis maritima, dealing principally with the 

 accessory chromosomes which are regarded as similar to an 

 equal pair of idiochromosomes. No detailed description of 

 chromosome behavior is given except that the 24 spermatogonial 

 chromosomes become reduced to 12. 



Stevens ('10) gives the results of her studies upon the sperma- 

 togenesis of Forficula auricularia. Briefly stated, her conclusions 

 are that the diploid chromosome number, including an unequal 

 idiochromosome pair, is 24. This, by a telosynapsis of the 

 typical insect character, produces a haploid number of 12. The 

 first spermatocyte prophase shows the chromosomes in the form 

 of loops, U's, rings and figures of 8, with an occasional cross. 

 A reduction division follows after the concentration of the chromo- 

 somes. Occasional variations in the number of second spermato- 

 cyte chromosomes are ascribed to precocious division of the small 

 idiochromosome. 



Sutton ('00, '02, '03) Baumgartner ('02), Nowlin ('08), Finney 

 ('08), Robertson ('08) and Carothers ('13) have studied various 

 species of Orthoptera in my laboratory and their interpretations 

 do not differ from mine in any essential respects. For this reason 

 I shall not enter further into a consideration of their work here. 



CONCLUSIONS 



With the results of the various investigators before us it is now 

 possible to draw comparisons and to arrive at conclusions. Such 

 comparisons may advantageously be made under the various 

 headings that have been used in outlining the results of individual 

 investigations. 



a. Relation between chromosomes of the first spermatocyte prophase 

 and those of the spermatogonium 



1. Concerning the relation existing between the chromo- 

 somes of the first spermatocyte and of the spermatogonium there 

 are three theoretical possibilities, (a) The chromosomes of the 



