GENERAL ORGANOLOGY. 



105 



sac whose closed end unites with the likewise closed i^osterior jjart 

 of the archenteron (now called also mesenteron or mid-gut) until 

 the separating wall disappears, whereupon mid- and end-gut com- 

 municate with each other, and the digestive tract becomes a canal 

 extending through the entire body. 



Divisions and Appendages of the Digestive Tract. — The part 

 which the archenteron takes in comparison with the ectodermal 



Fig. 6(1. 



Fio. 59.— Bee-larva just after hatching : seen from the ventral surface. The diEes- 

 tive tract consists of three portions; a, fore-gut; m, mid-gut; c, hind-gut (not yet 

 connected with the mid-gut); xg, limits of segments; .s(, stigma; f, trachea; », 

 ventral nervecord. (After Butschli.) 



Fia 60 —Digestive tract of the domestic fowl, a, oesophagus ; h, crop; c, glandular 

 stomach; d, gizzard; e, liver; /, gall-bladder; y, pancreas; ;i, (, small mtestme; 

 7c, cgeca; 7, large intestine ; //(, ureters; j(, oviduct ; o, cloaca. 



proctodfBum and stomodfeuni in making up the completed diges- 

 tive tract is very different iu the various groups. On one side the 

 Crustacea, on the other side the vertebrates, offer the strongest 



