THE YOUNG NATURALIST. 



97 



Taking the above to be correct, let us apply it to the species under consid- 

 eration, all of which be it remembered, emerge in the cold stormy months 

 from October to March, being in consequence more liable to accidents and 

 unfavourable circumstances at the time of their emergence than any other 

 species, and therefore have a large proportion of crippled specimens, a fact I 

 can vouch for. Owing to the time of their appearance these species also 

 suffer very much from the attacks of insectivorous birds, which being on short 

 commons at that season of the year, search with surprising diligence in quest 

 of food, going round and round the tree trunks, looking into almost every 

 chink and cranny with a perseverance enough to drive an entomologist almost 

 frantic, as visitors to Richmond Park after Nyssia Mspidaria well know, for 

 the " wretched tree creepers " seem to flit along in front of every tree, and it 

 is not much use searching after they have finished. 



Let us suppose that long ago, perhaps in those prehistoric times in which 

 geologists revel, these species had winged females of the ordinary type, and 

 with each brood a certain number of "cripples" of both sexes appeared. 

 Now these " cripples " would be much better able to secrete themselves from 

 the birds than their winged companions, and consequently in the struggle for 

 existence they would stand a better chance, therefore, in the course of time, 

 were no other causes at work we should have a race of " cripples " as the 

 result of the survival of the fittest ; but, as the males always seek the females, 

 the " crippled " males would stand little chance of propagating their pecu- 

 liarities, while the accident of being unable to fly would not affect the 

 " crippled w females as the males would seek them out ; therefore, we find 

 that the more " crippled " a female was the greater chance she had of surviv- 

 ing and propagating, while the more perfect the wings of the male the more 

 chance he had of finding a mate, thus we have the females developing less and 

 less wings and the males more and more, untill we arrive at wingless or 

 almost wingless females, and males with very large wings in proportion to 

 their bodies. Having thus briefly outlined my theory I shall be glad to see 

 the subject taken up in these pages. I am aware of many arguments on the 

 other side, but will leave others to advance them. One of the chief will, no 

 doubt, be that this theory will not fit the females of 0. antiqua and 0. gono- 

 stigma. In these cases the same effect has probably been arrived at in a 

 different manner, but I think I have said sufficient in introducing what to me 

 seems a very interesting subject, and shall now take leave of it, in the hope 

 that next month's number will contain the opinions of others. 

 Devonshire Road, Hackney, London, 



