68 



Tlie Larva of Chironomus 



conformity with the wall of the body, the concavity 

 being turned towards the oesophagus, which lies between 

 them. The lining epithelium is not continuous through- 

 out, but ceases along the middle of the broad surfaces. 

 The cells form a single layer, and are of large size, while 

 the nuclei are enormous, being easily studied with a 

 quarter-inch objective (fig. 50, 5). Sometimes the cells, 

 probably in a special phase of activity, are flattish, while 

 at other times the nuclei, surrounded by a thin coat of 



Fig. 50. — Salivary glands of larva, i, position of glands on either side of 

 oesophagus and dorsal vessel. 2, transverse section of gland, showing the dis- 

 position of the secreting cells. 3, two epithelial cells. 4, epithelial cells stand- 

 ing ont into cavity of gland. 5, nucleus of epithelial cells, the last from 

 Balbiani, 1881. 



protoplasm, project into the lumen of the gland, being 

 connected with the wall only by a slender neck \ Bal- 

 biani 2 has described the very interesting nuclei of these 

 glands. They are easily prepared for examination, and 

 the object is well suited in every way to the young 



' The projection of the nuclei of these cells into the cavity of the gland 

 seems to be an extreme case of what may be noticed elsewhere ; for instance, 

 in the epithelium of the Malpighian tubules, and sometimes in certain 

 cells of the epidermis, especially iu those of the anal blood gills. Occasion- 

 ally small cells have been noticed in the basal portions of the epithelium, 

 as if for replacement of the existing functional ones. 



" 1881, p. 637. 



