PROCESS OF PUPATION 



659 



(Fig. 615, ?). The two leaves then fuse together and decay as at 

 the surface of the tarsus. 



Finally, in the mandibles and the labrum, there is only a cellular 

 thickening without any invagination. 



FIG. 614. Section through the anterior region of the head of Pieris larva, four days after the 

 8d moult : o, esophagus ; m, m, 1st maxillae containing the two imaginal buds of the tongue ; p, p, 

 labial palpi ; Tr, trachea. 



Process of pupation. Notwithstanding the great number of per- 

 sons who have reared Lepidoptera, close and patient observations as 

 to the exact details are still needed. Gonin, who has made the 

 closest observations on Pieris, pertinently asks why the antennae, 



FIG. 615. Section through the same place as in Fig. 614, 10 days after the 3d moult, the imaginal 

 appendages having grown in size : r, r, caducous folds of the old hypodermis and of the envelopes. 

 Other letters as in Fig. 614. This and Figs. 613-614, after -Gonin. 



which are appendages of the head, are visible in the abdominal 

 region, and why the tongue (maxillse) is extended between the legs 

 as far as the 3d abdominal segment. To answer these questions he 

 made a series of experiments. Selecting some caterpillars which 



