isiOTES ON AMPHIDASYS BETULAKIAi 



31 



to-night for exhibition. I never saw var. douhJedayaria aHvc, and 

 therefore I fear that Hke the memorable and exhaustive book on 

 Icehmd, in which an extended heading for a chapter was made, " On 

 the OAvk of Iceland," the chapter consisting of the one laconic sentence, 

 " There are no owls in Iceland," as far as I am concerned I can only 

 say : I know nothing about doubledaijaria. Harking back to the 

 question of sex, as influenced by food, I would suggest that the reason 

 why more females were bred from lime, is that the leaves of that tree 

 are more succulent and more easily masticated by the larva, which con- 

 sequently is better fed. The production of queen bees seems to 

 depend largely on the grub getting more nourishing food than the 

 Avorker larva, and the production of female newts and frogs is likewise, 

 I understand, greatly influenced by the supply of food obtained by the 

 tadpole — semi-starvation producing males, and the addition of meat 

 extract to the water producing females, whilst in extreme cases, where 

 the tadpoles were kept in filtered water, they did not develop at all. 

 It therefore seems reasonable that something of this sort acted in the 

 case of betularia when fed on lime instead of plum. *•* 



* We would call the attention of our correspondent to the fact that a lepidopterous 

 larva, when newly hatched, has the generative organs (of course, at this time, very 

 imperfectly developed) distinctly male or female, and that, therefore, it is impos- 

 sible to influence the sex of lepidoptera by any course of feeding that the larva may 

 undergo. — Ed. 



On the DevelQ,pment of Sex in Social Insects. °" 



By J. W. TUTT, F.E.S. 



I have, in a previous article {Ent. Eec', Vol. vi., pp. 181 — 182), 

 alluded to the Weismannian theory of " intraselection," tiz, that 

 just as there is a struggle for survival among the individuals of a race, 

 in which the fittest are victorious, so there is also, among the living 

 particles which make up the tissues and organs of each individual, a 

 similar struggle with a similar result. Weismann further considers 

 that structures which are undergoing modification — i.e., "adaptive 

 structures " — are not themselves transmitted, but only the " quality of 

 the material from which intra-selection forms these structures anew in 

 every individual life." 



It has been necessary to assume some theoretical position with 

 regard to the structure of compound bodies, and hence the smallest 

 conceivable particles of which living tissue is composed have been 

 variously named " gemmules " by Darwin, " biophors" by Weismann. 

 Peculiarities of these biophors, Weismann tells us, are transmitted, 

 and may " become more and more favourable and adaptive in the 

 course of generations if they are subject to natural selection." These 

 peculiarities as to sensitiveness in certain directions are inherited, 

 but the special direction which the particular growth takes in conse- 

 quence of this inherited sensitiveness is not inherited, but must be 

 acquired anew, so Weismann considers, in every individual life. " The 

 great significance of intra-selection, appears to me," he says, " not to 



* Part of a Paper read before the Lancashire and Cheshire Entomological Society, 

 Jan. 13th, 1895. [For previous part, see Ent. lice, Vol vi., pp 181-188]. 



