XI 



PHYLUM ARTHROPODA 



593 



processes of digestion are carried on in an elongated chamber with 

 glandular walls the chyle stomach or chylific ventricle (cd) which 

 may be divided into several parts. Sometimes between the crop 

 and chyle stomach is intercalated a muscular-walled chamber, fre- 

 quently containing chit-moils teQth,theprovcntriculus or gizzard (pr.). 

 Appended to the chylific ventricle at its anterior end are, in many 

 Insects, a number of tubular blind pouches, the hepatic cce-ca. At 

 its junction with 



the small intestine, ^,_ /a, cf 



or further back, 

 there open a num- 

 ber (from 2 to over 

 100) of narrow tubu- 

 lar appendages, the 

 Malpighian tubes 

 (vm.), which are the 

 organs of renal ex- 

 cretion. In the cases 

 in which the de- 

 velopment of the 

 alimentary canal has 

 been traced, it has 

 been found that the 

 Malpighian tubes 

 mark th- point 

 where the meseii- 

 teron passes into the 

 proctodseum, and it 

 is assumed that this 

 holds good gene- 

 rally. The lumen 

 of the tubes is 

 sometimes filled up 

 with cells. In some 

 insects, the Mal- 

 pighian tubes open 

 into a paired or 

 unpaired sac the 

 urinary bladder. 



The intestine is usually elongated, its posterior portion (cd.) i 

 dilated to form a wide rectum (r.), which opens on the exterior 

 by an anal aperture situated on the ventral side of the lasl 

 segment of the abdomen. Anal glands (ad.), producing an 

 odoriferous secretion, often open into the rectum. 



The tracheal system (Fig. 482) communicates with the ex- 

 terior through a number of apertures the stigmata (st.) which 

 vary in the details of their arrangement in the different orders 

 VOL. ( Q Q 



Honey-bee. 



the three pairs of legs ; 



4so Nervous, tracheal and digestive systems of the 

 a. antenna ; av, compound eye ; 61, 2 , 3 , 

 chylific ventricle ; ml, hind-gut ; 

 rd rectal glands ; st. stigmata ; 



iTvestele "ofTi^he'ai; system; m, malpighian vessels. 

 (From Lang's Comparative Anatomy.) 



IS 



