396 Miscellaneous. 



from the first large cells with brush-like edge belonging to the mid- 

 gut right at the top of the proventricular chamber. This agrees 

 with Cuenot's opinion in 1895 with regard to several Orthoptera. 

 Furthermore, while spreading over the cuticle of the external wall 

 of the tube, in intimate connexion with the latter, it passes into a 

 verj- elegant lamina, which has not been described. It is also 

 through the annular space enclosed between the tube, whose wall is 

 thickened to form a solid ring, and a second chitinous external ring 

 secreted by the wall of the mid-gut that the secretion-products of 

 the proventricular caeca flow (well figured diagrammatically by 

 A. Schneider). The arrangement is complicated by a little truu- 

 cately conical ring arising from the wall of the tube, and which 

 separates the internal chitinous ring from the external plastic chitin 

 of the membrane. The whole structure is shown up in sections by 

 the diiferences of power of taking the stain displayed by the cuticle 

 of the tube and rings and that of the still plastic peritrophic chitin. 

 Below this passage the membrane becomes consistent and very thin. 

 It is continually induced to go forward by the pressure of the food 

 driven out of the oesophagus by the action of the circular muscles. 



III. Existence of Vibnitile Cilia in the Mid- and Hind-Gut of the 

 Larva of Chironomus. — It is necessary to examine a number of 

 animals in order to find and fix these in a perfect state. Examina- 

 tion would be impossible in the absence of transparent tissues. 

 The cilia are found at the opening of the proventricular cseca in the 

 three regions into which the chylific stomach is divided — in the first 

 two on the brush-like edge, in the third (where the Maljughian tubules 

 open) on the cellular wall, devoid of platform (plateau). It is very 

 interesting to determine that the platform is never wanting in the 

 first two regions, when one cannot see • the cilia, but when these 

 exist they may be planted directly on the cell. This simplification, 

 here accidental, is comparable with the observations of Engelmann 

 in 1880 and of Frenzel in 1886, who look upon the component parts 

 of the brush as an immobile proximal segment forming an integral 

 portion of the whole and completely differentiated ciliary apparatus. 

 As there exists in the animal kingdom an infinity of non-ciliated 

 cells with a platform, the larva of Chironomus takes an intermediate 

 position in which the platform is probably only ciliated in a certain 

 number of individual cases. 



Cilia also are present in the hind-gut on the chitin, which is very 

 thin. They are only found sparingly at the beginning, and particu- 

 larly so in the widened part, where it joins the mid-gut. 



I shall give more details of the anatomy and histology of the 

 alimentary canal in this larva in a note which I shall publish 

 shortly in the ' Archives de Zoologie experimentale.' — Comptes 

 Rendus, t. cxxviii. (1899) pp. 1596-1598. 



