THE SALIVARY APPARATUS OF CIMEX 515 



the posterior portion by a well-marked constriction which is almost 

 constant in position. In the fasting condition this part of the gut is 

 usually filled with bubbles of gas, and contains also a few granules of 

 black pigment. When the bug feeds it is this part which receives the' 

 blood, and it is to the great distension of its lumen that the rotundity 

 df a fully gorged specimen is due. 



The posterior part of the gut, or the proximal intestine, is roughly 

 about twice as long as the cardia, and is coiled up in the posterior part 



of the abdomen. Its diameter is very variable and its 



The hind-gut 

 contour irregular, as the tube is divided up into a 



number of compartments, which are quite inconstant in position, by 

 contractions of isolated bands of circular muscles fibres. It never 

 contains fresh blood, which is retained in the cardia by the sphincter 

 muscle during the first part of digestion, but always contains a large 

 amount of a fluid with a heavy suspension of brownish black granules-** 

 the remains of the last meal. 



The cells of the wall of the mid-gut are of the usual secreting type. In 

 the anterior portion they are columnar in the resting condition, and 

 flattened when the gut is filled with blood, while in the posterior paft 

 they are cubical. In both situations, however, they exhibit great vari- 

 ation and irregularity in form, on account of the changes which occur iri 

 the secretion and excretion of the digestive juices. No peritfdphic 

 membrane has been described, though it may exist. 



The rectum is relatively large, and is pear-shaped. It always contains 

 a quantity of the same black granule-containing fluid which is found in 

 the portions of gut anterior to it, and is often very much distended. It 

 has a chitinous lining, as in the Diptera. There are no rectal papillae. 



The Malpighian tubes are four in number, and are inserted separately 

 into the gut at the anterior end of the rectum, their low insertion being a 

 remarkable feature. They are of the usual structure, and have crenulatdd 

 margins as seen in the proximal portions of the tubes in Philaematomyia. 

 The tubes are of uniform diameter and appearance throughout. 



The salivary apparatus of the bed bug consists of at least two pairs df 

 glands with extremely long and delicate ducts, and a salivary pump iri 

 the head. The two pairs of glands may be distin- 

 guished for the sake of convenience as the ovoid and apparatus 

 cardiac glands respectively. The ovoid glands (Plate 

 LXIV, fig. 7) lie at each side of the anterior end of the stomach, slightly 

 anterior to the junction between the metathorax and the first abdorriinal 

 segment. When distended with secretion they are ovoid or pear-shaped, 



