239 



the chylific ventricle, with its glandular envelope, is probably 

 the true digesting portion, and the posterior part serves for the 

 absorption of cliylified fluid. 



The course of the chylific ventricle is straight. Its length, 

 in contracted alcoholic specimens, is about 25 mm. ; its diameter, 

 1.5 mm. Owing to its tough muscular substance, it is supposed 

 to be capable of extension and contraction, and to have peri- 

 staltic motions, in the living animal. 



The chylific ventricle terminates with a sort of sphincter, 

 reaching into the third and last part of the alimentary system, 

 the rectal bladder (Fig. 4 g^. 



The rectal bladder is of the same form as the inoluvies 

 and, like the latter, is a capacious organ with thin, chitinous 

 walls. Its widest lumen is toward the chylific ventricle, 

 and it gradually narrows to within about 3 mm. from the anal 

 orifice, to which extends a narrow muscular tube. Shortly be- 

 fore reaching this tube the rectal bladder is provided with gland- 

 ular, longitudinal folds like those mentioned in the pharynx. 



Six ellipsoidal bodies, rectal cells (Fig. 4 A), equidistant 

 from each other, form a sort of girdle around the widest part 

 of the bladder. Similar organs have been observed long since 

 in other insects, and much has been written about them, to which 

 I can add but little. Omus has them. Their physiological 

 action has not been sufficiently explained, though, in general, 

 they are regarded as excretory organs. 



The rectal cells of Amblychila are 2 mm. long, and about 

 0.9 mm. wide (Fig. 5), and have a chitinous, lemon-colored 

 wall, consisting of four layers (Fig. 6). The central part is 

 filled by a simple cell-layer, consisting of an aggregation of 

 large, colorless cells, closely packed and therefore appearino- 

 oval-polygonal. The outermost layer of the wall is the nar- 

 rowest, and is colorless and structureless ; the second is one- 

 half broader, colorless and structureless ; the third is as broad as 

 the two outer together, yellow, convex outwardly and structure- 

 less ; tb.e innermost is as broad as the second outer, yellow, and 

 exhibits under high power, glandular canals running toward the 

 large central cells. The latter are plainly nucleated. 



