282 GENERAL KEALIKA'S. 



they were members from Thysanura, as has been 

 stated above ^ with reference to the saltatorial Orthop- 

 tera, but the researches of Brauer, Packard, and Lub- 

 bock, demonstrating that the secondary krrval stages, 

 grubs, maggots, etc., are modifications of the Thy- 

 sanuriform larval stages, show that this use of them 

 cannot be admitted. If this be granted, it becomes 

 possible to account for the phenomena as follows. 

 The modified, and adaptive, larval characters of the 

 grubs, caterpillars, etc., having become fixed in the 

 organization of such groups as the weevils among 

 Coleoptera, and in some whole orders, as in the 

 Lepidoptera and Diptera, have been inherited at such 

 early stages in accordance with the law of acceleration 

 in development that they have replaced the useless 

 Thysanuriform stage. In other words, the absence of 

 this primitive larval stage in the young of many spe- 

 ciahzed forms of insects now living is due to the ten- 

 dency to earlier inheritance of the later acquired, 

 adaptive characters of the secondary larval forms. 



It is very important for these considerations to 

 notice that after the insects possessing the indirect 

 modes of development have passed through their re- 

 ductive secondary larval stages, they return to the 

 more normal or direct mode of development in the 

 pupa. In doing this, they clearly illustrate the excep- 

 tional and adaptive nature of their deviations from 

 the direct mode during the larval stages, and show 

 that this resumption of the older beaten path marked 

 out by heredity is essential in order that a typical hex- 



1 See p. III. 



