g6 PAULINE H. DEDERER. 



connective tissue, which extend from the outer or convex side of 

 the organ, and converge towards the " hilus," where each lobe 

 opens into the sperm duct. The mature cells lie near this point. 

 Spermatogonia are massed closely together at the opposite end, 

 and the cells in the growth stage are grouped together in rounded 

 cysts which lie free in the lumen of the lobe. 



Methods. 



Upon removal of the dorsal abdominal wall, the testes were 

 quickly dissected out and transferred immediately to the fixing 

 fluid. Corrosive-acetic, Gilson's alcohol-chloroform-acetic, and 

 Flemming's fluids were used. The two former fixing agents proved 

 especially good for spireme stages, but achromatic structures were 

 more clearly defined with Flemming's fluid. The sections were 

 stained with iron haematoxylin, with which it was possible to dif- 

 ferentiate the plasmosome, or true nucleolus, from the chromatic 

 nucleolus. Thionin was also used, but did not differentiate so 

 clearly. 



The figures for this paper are, with the exception of Fig. I, 

 from camera drawings made with compensating ocular No. 8, 

 with a tube length of 160 mm., and J^ oil immersion lens. They 

 were enlarged 2\ diameters with a drawing camera, corrected 

 from the original, and then reduced one half in the final plates. 



General Development. 



Owing to the long period of development, it is not possible to 

 find all stages of germ cells in any one testis. In material fixed 

 during the winter, the series ranges from spermatogonia to per- 

 haps only the first spermatocyte prophase, while in testes fixed 

 in early June, about one week before emergence, nearly all of the 

 cells are transformed into spermatids and spermatozoa. 



There are several interesting points of general development to 

 be observed in the winter material. A varying amount of disin- 

 tegration takes place in the cells. A few first divisions appear in 

 the autumn pupse, but at a later period none are found, so that it 

 is probable that these are precocious first divisions, which are 

 followed by disintegration, while the permanent division stages 

 appear in the spring. This observation differs from that of Wil- 

 cox, who found in Caloptenus that " if cells reach the sperma- 

 tocyte stage they complete their course." 



