652 C. E. McCLUNG 



VII. Discussion of results on the spermatocytes 679 



a. Acrididae 680 



b. Locustidae 689 



c. Gryllidae 691 



d. Blattidae 692 



e. Phasmidae 695 



f . Forficulidae 695 



VIII. Conclusions. . . .' 696 



a. Relation between chromosomes of the first spermatocyte prophase 



and those of spermatogonium 696 



b. Composition of chromosomes in first spermatocyte prophase 700 



1. Rod-shaped tetrads 701 



2. 'V-shaped tetrads 702 



3. Cross-shaped tetrads 703 



4. Ring-shaped tetrads 703 



c. Relation of chromosomes of first spermatocyte metaphase to those 



of the prophase 707 



d. History of the tetrads in first spermatocyte mitosis 707 



1. Rod-shaped teti'ads 707 



2. V-shaped tetrads 708 



3. Cross-shaped tetrads 708 



4. Ring-shaped tetrads 710 



Hippiscus type 710 



Stenobothrus type 716 



e. The chromosomes in the second spermatocyte 718 



1. Hippiscus type 719 



2. Stenobothrus type 720 



List of Orthoptera whose spermatogenesis has been described 723 



Bibliography of Orthopteran spermatogenesis 725 



INTRODUCTION 



Since the beginning of investigations into the phenomena of 

 the maturation processes there have been conflicting views 

 regarding the nature of the two mitoses which so closely follow 

 each other without the customary resting stage intervening. 

 Almost from the first this period in the history of the germ cells 

 has been assigned great importance and a necessity for a thorough 

 understanding of the facts has been realized. Among those 

 possessed of an intimate knowledge of the complicated changes 

 here taking place there has come to be a general agreement that 

 of all the cell parts the chromatin gives every evidence of being 

 primarily important. Along with this has arisen the conviction 



