OBSERVATIONS ON COLEOPTERA. 



'79 



ning of the period of preparation there is a rapid change, chroma- 

 tolosis of the nucleus, a marked shrivelling and decrease in size, 

 and the cytoplasm becoming entirely vacuolated (Fig. 2, E). As 

 ecdysis begins and the old cuticula separates from the hypodermis 

 the contents of these glands are forced out between the old cutic- 





c 



(9) . 



FIG. 2. /.. decinilineala. Five stages in the development of the exuvial glands. 

 A, young stage showing rapid growth of nucleus in hypodermal cell ; B, later 

 stage showing cell much enlarged and projecting below the hypodermis, taken just 

 before second ecdysis; C, third stage just after second ecdysis, showing the cell as a 

 fully developed unicellular gland with outlet to surface ; D and E show the great 

 increase in size of these glands preceding pupation (at E is shown glands extruding 

 their contents to form part of the exuvial fluid) ; <', primary cuticula; r 2 , secondary 

 cuticula; h, hypodermis; ii>, basement membrane. 



