GENERAL REMARKS. I'i^) 



manifestation of new modifications and adaptive char- 

 acters as the adult, and often perhaps more variable. 

 This is an exceptional rather than the usual aspect 

 of the larval stages, and makes the study of insects 

 remarkably difficult and interesting. 



Sometimes in the orders I. to IX. (Coccidae, Ci- 

 cada), as well as more generally in X. to XVL, the 

 lan^ae carry the line of development and modification 

 a long way outside of what can be termed the normal 

 or direct course, but these deviations lead, as a rule, 

 back again through similar pupae to the same goal in 

 the imago, a typical adult insect. Epicauta, the 

 blister-beetle, is a good example (see pp. 157-159). 

 Fig. 98 shows the active Thysanuriform larva, and 

 Figs. 102, 106, 107, the grub-like larva w^iich passes 

 through two stages (Fig. 108, representing one stage) 

 before becoming the true pupa (Fig. 112) that trans- 

 forms into the imago (Fig. 113). These complica- 

 tions were probably due originally in each type to the 

 plastic nature of the organism, which enabled it to fit 

 itself to different conditions and surroundings during 

 its passage through the younger stages of growth. The 

 history of parasites, whose loss of parts and correlative 

 modifications are plainly adaptations to the nature of 

 the surroundings in all branches of the animal king- 

 dom, shows this to be sound reasoning. Among some 

 of these types there are all kinds of metamorphoses 

 and very complicated modes of development, so that it 

 is not difficult to surpass even those of insects. One 

 can apply a similar nomenclature and the same laws 

 in explanation of the often curious and sometimes 

 extraordinary metamorphoses, and these changes are 



