THE COCKROACH. 353 



ventriculus (Fig. 98, f), an elongated tube, the junction of 

 which with the intestine is marked by the insertion of the 

 numerous Malpighian tubes. The anterior end of the ven- 

 triculus is provided with seven or eight caecal diverticula of un- 

 equal lengths (Fig. 98, e), the pyloric cceca. The first portion 

 of the intestine {ileum) is narrow. The next, termed the 

 colon, is very wide, and somewhat sacculated. A constric- 

 tion marks off the region of the colon from the straight short 

 rectum (Fig. 98, i), which terminates in the anus, situated 

 at the hinder extremity of the body between the podical 

 plates. 1 



The aperture by which the mouth communicates with the 

 gullet is small, and situated at the superior and anterior part 

 of the buccal cavity. A broad projection of the posterior and 

 inferior wall of the buccal cavity occupies all the space between 

 the oesophageal opening of that cavity and the labium, and 

 ends in a free subcylindrical process. This is termed hypo- 

 pharynx or lingua, but it might be well to reserve the term 

 lingua for the free end, and hypopjharynx for the attached 

 posterior portion. The anterior surface of the hypopharynx 

 slopes downward and forward; its sides are supported by two 

 sclerites, which are narrow and rod-like above and broad be- 

 low, where they unite in an arch on the dorsal face, just where 

 the free part, or lingua, begins. On the under side of the lin- 

 gua are two broader sclerites, which also unite and form an 

 arch, which lies over the opening of the salivary duct. The 

 anterior surface of the lingua and hypopharynx is beset with 

 fine hairs. 



The two salivary glands, with their receptacles, are greatly 

 developed in the Cockroach. 2 The glands (Fig. 98, I) lie on 



1 M. F. Plateau ("Eecherches sur les phenomenes de la digestion ehez les 

 Insectes," 1S74 ; "Note sur les phenomenes de la digestion chez la Blatta 

 amerieaine [Periplaneta Americana]," 1870 ; and " Recnerches sur les pheno- 

 menes de la digestion chez les Myriapodes," 1876) divides the alimentary canal 

 of insects and myriapods into a buccal, a median, and a terminal portion. The 

 buccal portion consists oftne oesophagus, crop, and proventriculus — which last 

 he considers to be a mere strainer, and to have no masticatory function. The 

 middle division lies between the proventriculus and the insertion of the Mal- 

 pighian tubes. The terminal division extends from tire latter point to the anus. 

 With the solitary exception of lulus, the secretions of the alimentary canal are 

 always alkaline,*and that which etfects the transformation of the albuminoid 

 elements of the food into peptones appears to be furnished by the middle di- 

 vision, which is lined by epithelium, devoid of any cuticle. In carnivorous in- 

 sects digestion may take place in the crop by the flow of the secretion of the 

 middle intestine into it. The salivary fluid of Blatta rapidly effects the trans- 

 formation of starch into sugar. 



2 The salivary glands are well described by Bascli, " Untersuchungen uber 

 die chvlopoietische und uropoietische Svsteme der Blatta orientalis." ("' Sitzb. 

 Wiener Akad.," 1858.) 



