CH. XI] 



THE REPRODUCTIVE SYSTEM 



213 



spermatozoa (s 2 ). On the ventral side, nearest the intestine, the 

 lobules are filled with ripe or nearly ripe spermatozoa (s 3 ) of an 

 elongated form. There do not seem to be any definite ducts to 

 the lobules ; we must therefore regard them as formed by foldings 

 and constrictions of the original gonad-wall. 



The process of spermatogenesis has not been studied in detail 

 in the Dragonfly, though the later stages in the growth of the 

 spermatozoa have been followed by Biitschli [20], in the case of 



ts- 



9 



10 



Fig. 92. Internal reproductive organs 

 of Aeschna brevistyla Ramb., <$, dorsal 

 view ( x 2). sr sperm-reservoir ; ts 

 testis; vd vas deferens; vn ventral 

 nerve-cord; 410 abdominal seg- 

 ments. Original, from a dissection. 



Fig. 93. L.S. through portion of testis 

 of a freshly-emerged male of Isch- 

 nura aurora Br., to shew lobules; 

 s x spermatidia; s 2 immature sper- 

 matozoa ; 5 3 ripe spermatozoa ( x 150). 

 Original. 



Agrion and Calopteryx. Fig. 94 shews a mature spermatozoon 

 of the latter genus. The head (h) is very short, - 01 mm., 

 cylindrical, with elongated nucleus (nu). The middle piece (m) 

 is five times as long as the head, and almost as wide. The tail (t) 

 is of great length, nearly 0*2 mm., excessively thin, and undergoes 

 violent lashings by means of which the organism is propelled 



