214 



ZOOLOGY FOR MEDICAL STUDENTS 



CHAP. 



perfect insect (Fig. 97, C), fitted for active movement and provided with 

 wings, legs, and other appendages. 



Investigation of the details of internal structure of the insect shows 



Life-history of a Cabbage Butterfly (Pieris). (From Graham Kerr's Primer of Zoology.) A, Larva 

 (Caterpillar) ; B, pupa or chrysalis ; C, Imago or adult. A , antenna ; abd, abdomen ; e, radiate eye ; 

 H, head ; l,p, labial palp ; mx.l, first maxilla ; s/, stigma ; Th, thorax ; W, wing. 



that many of these undergo quite as profound an alteration during 

 metamorphosis as does the external form. 



It would appear to be a common feature of all animals except the 

 simplest that there is constantly taking place during the period of active 



