36 PRED\CIOUS AND PARASITIC 



the Syrphida {Erista/is tenax) says of larval adaptation generally : 

 "Adverse surroundings may be successfully combated by larvsei 

 and we may therefore conceive that certain organs may become 

 profoundly modified so as to meet the requirements necessary for 

 the struggle in life. The study of larval history will thus appear 

 to become more and more important, as these facts are generally 

 admitted " 



Sir John Lubbock, in his excellent treatise on the Origin and 

 Metafuorphoses of Insects, maintains the proposition " that the form 

 of the larva depends very much on the conditions of life," and 

 after an able argument, based on many apt examples, he concludes 

 " that the form of the larva in insects, whenever it departs from 

 the hexapod Campodia type, has been modified by the conditions 

 under which it lives. The external forces acting upon it are dif- 

 ferent from those which affect the mature form, and thus changes 

 are produced in the young which have reference to its immediate 

 wants rather than to its final form." 



" And lastly, as a consequence, that metamorphoses may be 

 divided into two kinds — developmental and adaptional or adap- 

 tive." In another place the same writer says: — "The metamor- 

 phoses of insects depend then primarily on the fact that the 

 young quit the egg at a more or less early stage of development ; 

 and that consequently the external forces acting upon them in this 

 state are very different from those by which they are affected 

 when they arrive at maturity." 



For my own part, I find it somewhat difficult to see how, 

 granting an evolutionary origin of species, a variation in the mode 

 of development, such as the ' incomplete ' metamorphosis pre- 

 sents, can be made a ground for separating insects which are so 

 clearly connected by important points of general structure, by 

 wing venation, and by resemblance of larval form and food (albeit 

 one is adapted for aquatic and the other for terrestrial existence), 

 as Calepteryx and Myrmeleoti, which are shown on Plate I., at 

 Figs. I and 2. 



Moreover, I would emphasise most strongly the point that the 

 metamorphoses of insects, although they have been divided into 

 four distinct stages by so many generations of naturalists that their 

 definite existence has become almost an article of faith, are in 



