1 82 NEEDHAM. [VOL. 1. 



appear almost as soon as the larva is done feeding. There is a 

 slight loosening of the cuticle, and contraction of the body away 

 from it, especially on the dorsal side of the thoracic segments 

 and of the head. The budding legs and wings, already visible 



through the transparent skin (Fig. 

 i), begin to grow and extend down- 

 ward. The fat at the interior end 

 of the body begins to lose its mottled, 

 slightly grayish appearance, and be- 

 comes homogeneous, translucent, 

 slightly yellowish-white. 1 



Then the larval skin is cast, and 



FIG. i. Full-grown larva of the flaff . . 



the pupa appears with all the adult 



w, wing buds, and /, leg buds, as seen appendages clearly recognizable. 



through the skin. J 



After this the progress of internal 



changes may best be gauged by pigmentation ; first, in the eyes, 

 then in the tips of the hind wings, and lastly in the general 

 integument. Some of the corresponding internal phenomena 

 will be discussed under the following headings. 



II. The Hypodcnnis during ]\IctamorpJiosis. 



The hypodermis of this weevil is not, so far as observed, 

 destroyed during metamorphosis to be again rebuilt hi any part. 

 The cells, however, while maintaining fairly constant relations 

 at their ends, externally with the covering cuticle and internally 

 with the tenuous basement membrane, take on remarkable variety 

 of form and show a fine capacity for shifting, massing, or scatter- 

 ing themselves, previous to the definitive formation of the adult 

 chitin. This might have been anticipated, in view of the ex- 

 quisite sculpture and ornamentation of the adult beetle. It 

 will be of interest to consider first briefly the origin of the 

 appendage buds ("imaginal discs"). 



Wings and legs appear at the beginning of the third larval 

 stage, each as a slight thickening of the hypodermis, showing 

 almost from the beginning a slightly concentric arrangement of 

 the elongating cells. Fig. 2, B, shows the beginning of a middle 



1 Correspondingly it ceases to be stained black with osmic acid in fixation. 



