Connective Tissue deficient 



87 



clearing and staining, the nucleus, the parietal pro- 

 toplasm, and the very numerous polygonal granules can 

 be defined. In the larvae of some species of Chironomus 

 the granules have a grass-green colour, which persists in 

 the pupa and in the newly emerged fly. In the larva of 

 C dorsalis such granules occur in smaller proportion. 

 The hmer layer surrounds the alimentary canal, and has 

 no segmental divisions. It is continuous from the hinder 

 part of the thorax, or the beginning of the abdomen, to 

 the ninth segment behind the head, ending opposite the 

 reproductive bodies. Like the outer layer, it is composed 

 of cells, packed into 

 irregular lobes or 

 strings, which show 

 bulges and constric- 

 tions, with many 

 cross-connexions. De- 

 tached cells and little 

 groups of cells are 

 also found. In older 

 larvae the cells be- 

 come charged with 

 oil-drops and gra- 

 nules. Nuclei are 

 easily demonstrated by clearing and staining; like the 

 containing cells, they are larger than in the outer layer. 

 The inner layer forms earlier than the outer, and is 

 conspicuous in the embryo. 



The trabecular connective tissue, which in most insects Connective 



tissue and 



invests the viscera, binds them together, and connects tracheal 

 them with the body-wall, is very poorly developed in the deficient. 

 Chironomus-larva, and seldom attracts the attention of 

 the anatomist. The paucity of tracheal tubes further 

 contributes to the lax and mobile condition of the organs 

 in the body-cavity. 



Fig. 58. — Inner fatty la.yer, from living 

 larva. The fat-drops arc shaded. Tree cells 

 take a spherical shape. 



