hi \ i I <M" 



161 



Imaginal Buds. The wiiij^s and let^s of a lly original*- in the hirva 

 in tin- form of rellular masses, termed ima^innl /Ws. Of lii-lob|;tsts, as 

 \\Vismann distovrred. Thus in the lar\,i ol < orrll/r.i. then- arc in 

 i';irh thorarir segment a pair of dorsal huds and a par itral buds 



arh l)iid brmij dearly an examination of the hypodrrmi- 

 atjhe bottom of a previous inva^inat ion. The -ix \vntral hud- form 

 the K-.US exentuallv; of the dorsal hud>. the middle and posterior jinir- 

 form. re>pei lively, the- win^s and the halteres, and the anterior pair 



FIG. 222. Diagram- 

 matic transverse section of 

 Corethra larva, to show 

 imaginal buds of wings (w) 

 and legs (/) ; h, hypoder- 

 mis; , integument. Modi- 

 fied from Lang's Lehrbuch. 



C D 



FIG. 223. Diagrammatic transverse sections of muscid 

 larvae, to show imaginal buds, h, larval hypodermis; i, larval 

 integument; ih, imaginal hypodermis; /, imaginal bud of leg; 

 w, imaginal bud of wing. Modified from Lang's Lehrbuch. 



form the pupal respiratory processes. Each imaginal bud is situated in 

 a pcripoddl cavity, the wall of which (peripodal membrane) is continu- 

 ous with the general hypodermis; as the legs and wings develop, they 

 emi me from their peripodal sacs and become free. 



In Corethra but little histolysis occurs, most of the larval structures 

 ;iu r directly into the corresponding structures of the adult. Core- 

 tit ra is, indeed, in many respects intermediate between heterometabo- 

 lous and holometabolous insects as regards its internal changes. 



Muscidae. In Muscidae, as compared with Corethra, the imaginal 

 huds are more deeply situated, the peripodal membrane forming a 



11 



