STUDIES OX INSECT SPEKMATOGENESIS. 55 



\vould have been exceedingly difficult, if not entirely impossible, 

 in the spermatids of " normal " size. This paper, therefore, deals 

 exclusively with the large-cell generations, but the results have 

 been checked in the small-cell generations and it is clear that the 

 phenomena are in both cases essentially the same, the factor of 

 size being the sole difference. I have used for this study three 

 forms Euschistus euschistoides Voll., Broch\incna quadripitstit- 

 lata Fab., and Murgantia histrionica Hahn, each of which pos- 

 sesses two testicular lobes of large-cell generations. 



I have made use particularly of three technical methods 

 Benda's alizarin-crystal violet stain and the Golgi methods of 

 Kopsch and Cajal, the reasons for employing these particular 

 methods being made evident by the descriptive section which fol- 

 lows. The first named was used exactly as described in the sec- 

 ond of these " Studies." The Kopsch method does not usually 

 impregnate the mitochondria, but occasionally the nebenkern and 

 its derivatives are blackened in the present case after an im- 

 mersion in 2 per cent, osmic acid of about ten days. The Cajal 

 formol-uranium nitrate method was used as described by Cajal, 1 

 with a primary fixation of 8 to 10 hours, followed by silver nitrate 

 (1.5 per cent.) for 36 or 47 hours, and reduction with hydro- 

 quinone for periods up to 24 hours. At best this method is a 

 rather capricious one. 



I have here to acknowledge the many helpful suggestions and 

 criticisms which have been contributed from time to time by 

 Professor E. B. Wilson. I am also indebted to Dr. Franz 

 Schrader for assistance in the collection of material, and par- 

 ticularly to Mr. H. G. Barber through whose unusual kindness I 

 was able to get the specimens of Brochymena which I have used 

 in this " Study." Mr. Barber has also identified all of my ma- 

 terial. 



OBSERVATIONS AND DISCUSSION. 



In an earlier work (Bowen, '22), I have given a detailed ac- 

 count of the manner in which the spermatid nebenkern is con- 

 densed from the originally thread-like (with some inter-mixed 



1 See Cajal, Algunas variaciones fisiologicas y patologicas del aparato 

 reticular de Golgi., Trab. Lab. Biol. Univ. Madrid, 1914, Vol. 12. 



