22 



ANIMAL BIOLOGY 



In the pupa the sheaths, or cases of many organs of the 

 butterfly, may be made out; the large wing cases lie at 

 the sides of the body; ventral to these are the cases of the 

 antennse which show indications of numerous segments; 

 next to the antenna cases are the cases for the first and 

 second legs, those of the third pair being overlapped by 

 other parts. Finally, in the middle line is the case for 

 the tongue. Aside from being able to move the abdomen 

 when it is irritated, the pupa is compelled to lead a sta- 

 tionary life. But while outwardly quiet the pupa is 



PIG. 15. The painted lady butterfly, Vanessa atalanta. 



by Essig.) 



(From photo 



undergoing a rapid and extensive transformation of its 

 organs. Old organs are being torn down, new ones are 

 being built up, and extensive changes of form are taking 

 place in other parts. So great are these changes that 

 the pupa may be compared to a ship which has to be laid 

 up for repairs. It is the workshop in which the caterpillar 

 is being made over into the very different form of a butter- 

 fly. Wings are grown; large compound eyes replace the 

 simple ones of the caterpillar; the biting and chewing 

 mouth parts are modified into the elongated nectar- 



