148 



The Pupa of Chironomus 



described in many insects 1. The cast basement-mem- 

 brane, or ' cyst,' observed in some other insects, .was not 

 found in Chironomus. 



The changes which take place are not wholly destruc- 

 tive. In the oesoi^ha.i^us of the larva the epithelium is so 

 thin as to require pains to make it evident, and even with 

 careful staining and high powers we rarely see anything 

 more than regularly spaced and minute nuclei. But in 

 the pupa a relatively thick epithelium with large nuclei 













Fio. 1 1 ^ —Stripped epithelium, from stomach of pupa. Tlio left-hand 

 figure shows scattered cells and nuclei ; the riglit-hand one the more 

 Tisual aijpearance of a coherent mass. 



is often conspicuous in sections (fig. 114). AVe have not 

 discovered how it is regenerated. 



Just above the junction of the oesophagus with the 

 stomach a hollow lateral outgrowth forms on one side. 

 shortly before pupation. It grows fast, and soon takes 

 the form of a ventral diverticulum (fig. 114). This is 



' Weism;inii. 1863; Kowalewsky, 1887, aiul authors there quoted; 

 Rengcl, 1896. 



