The Structure and Special Physiology of Insects i 5 



tilization is itself accomplished in the lower end of the egg-duct just before the 

 egg is laid, by the escape of spermatozoa from the spermatheca (the female 



saLg.. 



..ea. 



.mi. 



FIG. 25. FIG. 26. 



FIG. 25. Alimentary canal of larva of harlequin-fly (Chironomus sp.). oes., oesophagus; 

 s.g., salivary gland; ca., cardiac chamber of stomach; ml., Malpighian tubules; ch., 

 intestinal chamber; 5/., small intestine; col., colon. (After Miall and Hammond; 

 much enlarged.) 



FlG. 26. Alimentary canal of two species of thrips; at left Trichothrips copiosa, male, 

 at right Aelothrips fasciata. sal.g., salivary gland; oes., oesophagus; prov., proven- 

 triculus; vent., ventriculus; m.t., Malpighian tubules; int., intestine; rec., rectum. 

 (After Uzel; greatly enlarged.) 



having of course previously mated) and their entrance into the egg through a 

 tiny opening, the micropyle (Fig. 67), in the egg-shell and inner envelopes. 

 A queen bee mates but once, but she may live for four or five years after 

 this and continue to lay fertilized eggs during all this time. She must 



