238 



EVOLUTION AND GENETICS 



Fig. 145. — Sting of honey-bee, x30. A, sting separated from its muscles; 

 ps, poison sac; pg, poison gland; 5lh g, fifth abdominal ganglion; n, n, 

 nerves; e, external thin membrane joining sting to last abdominal segment; 

 i, k, I and i , A; , Z , levers to move the darts; sh, sheath; v, vulva; p, sting 

 palpus or feeler, with tactile hairs and nerves. B and C, sections through 

 the darts and sheath, x300; sh, sheath; d, darts; b, barbs; /;, poison chan- 

 nel. D, end of a dart, x200; o, o, openings for escape of poison. (From 

 Packard, after Cheshire.) 



