ORTHOPTERAN SPERMATOGENESIS 657 



c. Comparisons 



1. Acrididae. The points of interest for this study regarding 

 the chromosome condition in the spermatogonia concern (1) the 

 number of chi'omosomes, (2) their sizes and forms, (3) the posi- 

 tions of their fiber attachments, (4) their arrangement in the meta- 

 phase plate and (5) their behavior in mitosis. I will briefly 

 give the results of other investigators and then compare them 

 with my own. 



Buchner ('09) reports 23 chromosomes in Oedipoda, all rod- 

 shaped, with terminal fiber attachment, and arranged in the 

 typical way. He is however unable to recognize homologous 

 pairs. Brunelli ('10) in Tryxalis finds 23 rod-like, radially ar- 

 ranged chromosomes of various sizes with terminal fiber attach- 

 ments, but no recognizable pairs. Davis ('08), from studies on 

 Dissosteira, Arphia, Hippiscus, Chortophaga and Melanoplus, 

 distinguishes the 23 typical chromosomes showing the paired 

 condition, radial arrangement and terminal fiber attachment. 

 Granata ('10), in Pamphagus, is able to find only 19 chromo- 

 somes, all of which are typically Acridian in their form and behav- 

 ior. Montgomery ('05) is the only investigator who reports 

 an even number of chromosomes in any member of this family, 

 and, in addition, a variation of the number within the genus. 

 This number is 20 or 24 in Syrbula acuticornis. In other respects 

 Montgomery's results are typical for the Acrididae, but the even 

 number requires the accessory chromosome to be bivalent. My 

 own students have invariably reached the same general conclu- 

 sions regarding the nature and behavior of the spermatogonia! 

 chromosomes. Thus, Carothers in Arphia, Brachystola and 

 Trimerotropis; Hartman in Schistocerca; Nowlin in Melanoplus; 

 Pinney in Phrynotettix; Sutton in Brachystola and Wenrich 

 in Phrynotettix find typical Acridian conditions throughout. 

 Robertson ('08) also, in Syrbula admirabilis, after a very careful 

 study, is quite unable to agree with Montgomery regarding the 

 number of chromosomes and the paired condition of the accessory 

 chromosome, and finds the chromosome behavior in this genus 

 typical of the group. 



