THE SPERMATOGONIAL DIVISIONS IN BRACHYSTOLA 



MAGNA. 



BY WALTER S. SITTON. 

 With Plates XXXII, XXXIII, XXXIV, XXXV. 



I.— Introduction. 

 II.— Material. 

 III. — Fixing and Staining Methods. 

 IV.— Terminology. 

 v.— Observations. 



VI.— Comparison of Literature and 

 Discussion. 



1. Origin of the Spermatocysts. 



2. Accessory chromosome. 

 'S. Sacculated nucleus. 



VII.— Summary. 



VIII.— Bibliography. 



IX.— Explanation of Plates. 



INTRODUCTION. 



npHE material for this paper was collected in the summer of 181)9, 

 ^ in Russell county, Kansas, together with testes from about thirty- 

 five other species of Acrididpe, for the purpose of making a study of 

 the spermatocyte divisions. However, before the material was pre- 

 pared, McClung's paper on "The Spermatocyte Divisions of the 

 Acrididse" appeared, and as, on examination of my material, I found 

 his observations and conclusions to be generally true, I decided to leave 

 that subject for a comparative study in a later paper, and to restrict 

 this publication to the spermatogonial divisions (with special atten- 

 tion to the chromatic elements) — a field which seems to have been 

 very generally neglected, and for which Brachysfola is especially 

 favorable. 



I have been fortunate enough to find in this material two struc- 

 tures or conditions which, so far as I know, liave never before been 

 described in germ-cells. One of these is the presence, in a certain 

 stage, of a distinct membrane around each chromosome and the ab- 

 sence of any general nuclear membrane (figs. 12, 13, 14, 30, 31, 32, A, 

 and (t ). and the other a vesicular arrangement of the chromatin in 

 one of the chromosomes. ( Figs. 31, 33, 34, 35, F, and J. ) Bi'tn/nj.^tolff 

 has also shown itself a favorable object for the solution of the i^roblem 

 of the origin of the spermatocysts. 



I wish to express here my gratitude to Prof. C. E. McClung, for 

 many valuable suggestions and for other assistance in the prosecu- 

 tion of this work, and in the making of the photomicrographs given 



[13.5]-K.U.Qr.— A ix 2-April, '00. 



