416 



or in the materials employed ; we may mention also remarks on 

 the habits of species in captivity compared with the same species 

 at liberty. 



In the amphibious reptiles, it would be desirable to have further 

 observations as to whether under any circumstances metamor- 

 phosis is arrested, and the adult state never arrived at ; or, on the 

 other hand, whether in some cases they are not born adults as 

 regards form and structure, the larva state being passed over 

 altogether. 



In insects, we need a closer investigation of their economy and 

 habits, especially of those that live in societies ; of their structure, 

 development, and transformations. We desire to know the rela- 

 tion of insects to the particular localities they inhabit ; how far 

 their characters are influenced by climatal or geological considera- 

 tions ; to what extent variation is connected with wide diffusion of 

 the species, and whether in any cases it is dependent upon the 

 food of the larva, or on the season of hatching in double-brooded 

 species. We want more facts throwing light on dimorphism and 

 polymorphism ; a record of any cases of abnormal modes of 

 reproduction ; inquiry to be made into the cause of barrenness in 

 the females of autumnal broods of Lepidoptera ; also respecting the 

 relative numerical proportion of the sexes in all insects generally ; 

 this last question to be especially taken up in the case of the gall- 

 making Cynipidse, in connection with their economy. Lastly, the 

 whole subject of mimicry, not merely as it occurs in insects, but 

 in all other classes of the animal kingdom as well, calls for much 

 further and long-continued attention in order to be thoroughly 

 understood. 



It is not expected, nor is it to be desired, that any one observer 

 should take up all these questions at once. The science of biology 

 will be best promoted by his selecting such as fall in with his 

 particular taste, the knowledge he already has of the subject, and 

 the habits of research he has been most used to. But, having 

 made his choice of one or more according to circumstances, let him 

 give his chief attention to these points, only gathering information 

 on others as it may come to hand. There is enough in any one 

 of these inquiries to employ the leisure hours of a man's life if he 



