278 GENERAL REMARKS. 



mal during the pupal stage have consequently changed 

 in proportion to these requirements from the active to 

 the quiescent condition. 



There are other series of facts equally important 

 and significant. While the Thysanuriform stage is 

 present more or less in Coleoptera and Neuroptera, 

 which have the indirect mode of development, it is 

 absent in the orders from XII. to XVI. inclusive, 

 having been replaced by the secondary larval stages 

 in accordance with the law of acceleration in develop- 

 ment. 



The tendency of the more specialized forms in the 

 orders I. to IX. to accelerate the development of 

 the earliest stages is shown in various ways. In the 

 grasshoppers,^ Mantidae, etc., the inheritance of the 

 adult pecuUarities of the type affects the young at 

 such early stages that, as has been described above,- 

 the primitive larval Thysanuriform stage is skipped, or 

 omitted from the development. 



In Coleoptera and in the highly specialized orders 

 of insects (XI. to XVI.) a novel and disturbing in- 

 fluence appears, due to the extraordinary importance 

 of the functions of larval hfe. This period in the 

 larger number of groups in other classes of animals is 

 much less variable than the adult stage, and it is really 

 very often a mere vehicle for the record and trans- 

 mission of hereditary characters. In some of the 

 orders of insects, however, it is as efficient for the 



1 Packard's illustrations on p. 60 of his Entomology for Be- 

 ginners give an excellent series of one species, Caloptenus 

 femur -riibrum. 



2 See p. III. 



