THE AMERICAN ENTOMOLOGIST. 



209 



cured scores in a single season. Any one 

 who will glance over the history of what 

 has been done in insect embryology will be 

 able to select a hundred examples as im- 

 portant and as easy to obtain as those al- 

 ready named, and by concentrating his 

 work upon them will do better service than 

 in an aimless selection of what may come 

 to his hand. 



In following the post-embryonal history 

 of insects there is work for all. While 

 allied forms have in general a very similar 

 development, there are so many which are 

 unexpectedly found to differ from one 

 another, that every addition to our know- 

 ledge of the life histories of insects is a 

 gain, and they are to be praised who give 

 their close attention to this matter. Here 

 is a field any entomologist, even the most 

 unskilled, may cultivate to his own advan- 

 tage and with the assurance that every new 

 history he works out is a distinct addition 

 to the science. The importance of an ac- 

 cumulation of facts in this field can hardly 

 be overestimated, and those whose oppor- 

 tunities for field work are good, should es- 

 pecially take this suggestion to heart. 

 Nor, by any means, is the work confined 

 to the mere collection of facts. How to 

 account for this extraordinary diversity of 

 life and habits among insects, and what its 

 meaning may be, is one of the problems of 

 the evolutionist. There are also here some 

 specially curious inquiries, to which Sir 

 John Lubbock and others have recently 

 called attention, and to which Mr. Riley 

 has contributed by his history of Epicauta 

 and other Meloidce. I refer to the ques- 

 tions connected with so-called hypermeta- 

 morphosis in insects. In these cases there 

 are changes of form during the larval pe- 

 riod greater than exist between larva and 

 pupa, or even between larva and imago, in 

 some insects. There are also slighter 

 changes than these which very many larvae 

 undergo ; indeed, it may safely be asserted 

 that the newly-hatched and the mature 

 larvae of all external feeders differ from 

 each other in some important features. 

 The differences are really great (when com- 

 pared to the differences between genera of 



the same family at a similar time of life) in 

 all lepidopterous larvae, as well as in all 

 Orthoptera which have come under my no- 

 tice. No attempt to co-ordinate these dif- 

 ferences, or to study their meanings, or to 

 show the nature of their evident relation- 

 ship to hypermetamorphosis has ever been 

 attempted. 



Not less inviting is the boundless region 

 of investigation into the habits of insects 

 and their relation to their environment. 

 The impulse given to these studies by the 

 rise of Darwinism, and the sudden and 

 curious importance they have assumed in 

 later investigations into the origin and kin- 

 ship of insects, need only to be mentioned 

 to be acknowledged at once by all of you. 

 The variation in coloration and form ex- 

 hibited by the same insect at different sea- 

 sons or in different stations, " sports," 

 the phenomena of dimorphism, and that 

 world of differences between the sexes, 

 bearing no direct relation to sexuality ; 

 mimicry also, phosphorescence and its re- 

 lations to life, the odors of insects, the re- 

 lation of anthophilous insects to the colors 

 and fructification of flowers, the modes of 

 communication between members of com- 

 munities, the range and action of the 

 senses,* language, commensalism, — these 

 are simply a few topics selected quite at ran- 

 dom from hundreds which might be suggest- 

 ed, in each of which new observations and 

 comparative studies are urgently demanded. 



The fundamental principles of the mor- 

 phology of insects were laid down by Sav- 

 igny in some memorable memoirs more 

 than sixty years ago ; the contributions of 

 no single author since that time have added 

 so much to our knowledge, notwithstand- 

 ing the aid that embryology has been able 

 to bring. Nevertheless there remain many 

 unsolved problems in insect morphology 

 which by their nature are little likely to 

 receive help from this source. Let me 

 mention three : 



The first concerns the structure of the 

 organs of flight. The very nomenclature 

 of the veins shows the disgraceful condition 



* Notice Meyer's beautiful studies on the perception of 

 sound by the mosquito. 



