DIGESTIVE SYSTEM. 6l 



of f-in., but is straighter and smaller in the queen, 

 and its sides are, in all cases, banded with constric- 

 tions that occur at regular intervals. The gastric 

 glands are placed in its walls, while the pollen grains 

 commonly found within it in abundance give to it a 

 yellow, or yellowish-brown, appearance. At its further 

 extremity it narrows considerably, and forms a pylorus 

 in passing into the small intestine (si, Plate I.), which 

 is here met by a considerable number of long and 

 narrow tubes (bt, Plate I.), lying in tangled spirals, but 

 which, nevertheless, enter the walls of the digestive 

 system with great regularity, their openings being 

 closely set, side by side, in a single encircling line. 

 They are, probably, excretory in function, removing, 

 like the liver in ourselves, impurities from the blood, 

 which are modified so as to be of service in the 

 work of digestion. Their structure is shown at 

 C, which gives a small portion of one of them, 

 magnified 450 times. These tubes are known as 

 Malpighian vessels, from the great anatomist, Mal- 

 pighi, who discovered them ; or are called biliary 

 or urinary tubes, according to the view which may 

 be taken of their office. The intestinal lining mem- 

 brane here undergoes an interesting modification ; it 

 is arranged in a number of longitudinal ridges, and 

 is set with small, though hard, chitinous teeth (D, 

 gt, Plate I.), frequently double-pointed, each about 

 1 in. in length. They are most easily seen in a 

 newly-hatched bee, before any food has been taken 

 to interfere with the view. The object of these, 

 in my opinion, is to abrade the growing points of 

 any pollen grains which have not sufficiently yielded 



