Chitinoiis 

 cuticle. 



36 



The Larva of Chironomus 



effectively employed whetlier tlie tail is in tlie tube or 

 out of it, owing to the power wliicli the larva possesses of 

 maintaining a regular flow of water through the tube 



(P- 3)- 



2. Epidermis and Chitinous Cuticle. 



In most parts of the body of the larva the chitinous 

 cuticle is transparent and flexible. In the head, however, 



Fio. 23.— I, Epidermis from ventral blood-gill of larva. 2, ditto from dorsal 

 wall. 3, portion of detaclied basement-membrane with dead cells, found float- 

 ing in the body-cavity. 



it is harder, and of deeper colour than elsewhere. In the 

 prothorax it attains its greatest thickness, perhaps for 

 the greater security of the bi-ain and the important 



Fig. j4.— Anal blood-gill of larva, showing epidermis and floating filaments. 



imaginal organs which develop within, and consists of 

 numerous layers. 

 Epidermis. The Underlying epidermis consists in part of a single 

 layer of minute and close-fitting cells, resting on a base- 

 ment-membrane (fig. 23). The epidermic cells are best 



