WENEICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 61 



enough of the pecuUarities of Phrynotettix will be described to render 

 clear any new terms made necessary by them. 



Wilcox ('94) and Davis ('08) have both given detailed descriptions 

 of the structure of the acridian testis and have given figures or dia- 

 grams to show the topography of the follicles of which the testes are 

 composed. It will therefore be unnecessary to reproduce such figures 

 and descriptions here. 



b. Outline of successive Stages. 



1. Spermatogonia. — The spermatogonia of Phrynotettix (Plates 

 1, 2, fig. 1-20) behave in a manner typical for the Acrididae as de- 

 scribed especially by Sutton ('00), and by Davis ('08). As Pinney 

 ('08) has shown, there are 23 chromosomes, of which 22 can be 

 arranged in pairs, leaving an odd one, the accessory chromosome 

 (McClung, '99), or monosome (Montgomery, '06). The paired chro- 

 mosomes may be referred to as the autosomes (Montgomery, '06). 

 All the divisions of the spermatogonia are mitotic and are usually 

 considered as equivalent to somatic mitoses. A detailed account of 

 these divisions is given on pages 87-90. 



2. Primary spermatocytes. — The daughter cells produced at the 

 final spermatogonial division, as is well known, are characterized, 

 among other things, by the growth-period and by the formation of 

 the reduced, or haploid, number of chromosomes. For distinguishing 

 the different stages in the prophases, Davis ('08) employed a non- 

 descriptive method, designating successive stages by the successive 

 letters of the alphabet. Here it seems advisable to use largely the 

 terminology introduced by Winniwarter and by Gregoire. 



The telophase of the last spermatogonial division embraces a series 

 of processes similar to those in the telophases of the earlier spermato- 

 gonial divisions. Following the telophase, a series of changes takes 

 place which results eventually in the formation of fine single threads. 

 This fine-thread stage may be called the leptotene stage (Winniwarter, 

 '00). Between the telophase and the leptotene stages occur changes 

 which are of the utmost importance in any attempt to solve the prob- 

 lems of synapsis and the individuality of the chromosomes. These 

 stages may be called the jjreleptotene stages (Gregoire, '07). There 

 may be distinguished an earlier (Plate 2, fig. 23, 24) and a later (Plate 

 3, fig. 25-27) preleptotbue stage. 



When the leptotene threads are first formed, they seem to be greatly 



