102 



THE GERM-CELLS 



H 



Fig. 49. Spermatozoa of various animals. [A-I, L, from BALLOWITZ; J, K, from VON 

 BRUNN.] 



A. (At the left). Beetle (Copris), partly macerated to show structure of flagellum ; it con- 

 sists of a supporting fibre (s.f.) and a fin-like envelope ( f.) ; n. nucleus; a. a. apical body divided 

 into two parts (the posterior of these is perhaps a part of the nucleus). B. Insect (Calathus], 

 with barbed head and fin-membrane. C. Bird (Phyl/op/reuste). D. Bird (Muscicapa), showing 

 spiral structure; nucleus divided into two parts (w 1 , ;/' 2 ) ; no distinct middle-piece. E. Bulfinch ; 

 spiral membrane of head. F. Gull (Larus) with spiral middle-piece and apical knob. G. H. Giant 

 spermatozoon and ordinary form of Tadorna. /. Ordinary form of the same stained, showing 

 apex, nucleus, middle-piece and flagellum. J. " Vermiform spermatozoon " and, K. ordinary 

 spermatozoon of the snail Paludina. L. Snake (Coluber}, showing apical body (a), nucleus, 

 greatly elongated middle-piece (?), and flagellum (/). 



