164 PROCEEDIXGS OF THE ACADEMY OF [Feb., 



of the first workers in the field, or fear of conflict with them. In com- 

 mon law a man is held innocent until he is proven guilty, but in scien- 

 tific thought we should consider a view erroneous until it is proven 

 to be correct to fact. That view which presents phenomena from the 

 simplest interpretation, which is based upon the broadest comparative 

 series of facts, and, above all. which admits of no exceptions in natural 

 sequence, is the one which in the end has the greatest probability of 

 maintaining itself, because the one most likely to be congruous with the 

 facts. 



1. — Spermatogenesis of Syrbula acuticornis Bruner. 



Testes of adults of this Acridid were collected at Austin, Texas, 

 in the middle of October, fixed in Flemrm'ng's stronger fluid, and 

 stained with iron hsematoxyline. For the identification of the species 

 I am indebted to Mr. James A. G. Rehn, of the Academj^ of Natural 

 Sciences, Philadelphia. A considerable number of testes were sectioned 

 and studied, whence it resulted that some of them contained ten bi- 

 valent chromosomes in the first spermatocytes, others twelve. I can- 

 not determine whether this is due to Syrbula acuticornis being a form 

 including more than one species, or whether it is a single species with 

 individual variation in the number of the chromosomes; the latter 

 alternative would be in contradiction to the condition maintaining in 

 most species. Because this point could not be explained, and because 

 good proof is necessary to establish the occurrence of indi^adual varia- 

 tion in the number of chromosomes, the following description is limited 

 to cells contained in the testes of one individual. 



Work has been done previously upon the spermatogenesis of Acri- 

 didse by Wilcox (1895), McClung (1900) and Sutton (1900, 1902). My 

 results are in essential agreement with those of McClung, except with 

 regard to the time of the reduction division. Carnoy (1885) was the 

 first to describe cell divisions of male germ cells in Acrididse, and figured 

 in detail spermatogonial mitoses. 



As in the Hemiptera each testis is composed of long tubular follicles, 

 but they are more numerous in number, the earlier stages of the sperm 

 cells placed at the proximal end of the follicle, and the later stages at 

 successively following regions of the follicle. As far as I have noticed 

 there is no difference between the cells of different follicles, beyond a 

 dimensional one. 



Two generations of spermatogonia are found in the mature testis, 

 the smaller of which is the last generation, and by division forms the 

 first spermatocytes. The intermediate body or cell-plate (Zivischen- 



