CHAP. 



24 INVEETEBEATA 



produced, and those variations are preserved which adapt the 

 organism at the right time to the new mode of life. 



A 



B 



ctr- 



FIG. 9. The stalked larva and adult form of A ntuhni mullispina. (After P. H. Carpenter.) 



A, larva. B, adult, 1>, Basal plate ; cir, cirrus ; jiin, pinnule ; /', (irst radial plate ; 

 r 2 , second radial plate ; r'J, third radial plate. 



If, then, the last stages in developmental history are, so to speak, 



