Half an hour 



before 

 changing. 



One hour Twelve Eighteen 



after hours. hours, 



changing. 

 Immediately 



pupation. FIG. 38. Changes in the nervous 

 system of a butterfly, illustrating 



mechanical " cephalization." (From Packard, 



after Newport.) 

 89 10 



Twenty- j || four 

 hours 



Forty-eight 

 hours. 



