8o 



The Form of Insects 



matospores) which divide to form hollow globes {sper- 

 matocysts) of cells. Within these globes lie the sperm 

 mother-cells {spermatocytes), which divide into two and 

 then into four sperm-cells {spermatoblasts^). These, 

 escaping through the split wall of the spermatocyst, are 

 transformed into the active sperm-cells {spermatozoa) 

 (47). Each spermatozoon consists of a nucleated 

 head and a long tail, by whose vibratory action the 



Fig. 55. — A. Tip of Cicad's ovipositor, highly magnified, a. from above; b. 

 from beneath. B. Section through ovipositor more highly magnified, a. 

 facets in natural position ; b. separated shovi-ing interlocking ridges and 

 grooves. From Marlatt, Bull 14 (n.s.) Div. Ent. U.S. Dept. Agr. 



cell is enabled to enter the egg of the female. The 

 male cockroach is remarkable in that his testes shrivel 

 up while he is still immature, the development of the 

 sperm-cells being completed in the vesicles. 



The sperm-vesicles are situated close together in 

 the centre of the body, above the sixth abdominal 



^ Or spermatids . 



