TPIE ENTOMOLOGIST. 559 



one sex or the other will greatly preponderate, where no 

 especial treatment was followed in the rearing. 



While, therefore, 1 do not think that the facts yet in onr 

 possession warrant the belief that the quality or amount of 

 food has any influence in determining sex in the individual 

 once out of the egg, I do believe, with Thomas Meehan, 

 Henry Hartshorne, and others, that there is a certain relation 

 between organic vigour and sex, and that the latter may be 

 determined in the offspring by the amount of vigour or vitality 

 — creative or organic force — in the parents, and that the 

 female is in some way connected with increased, and the 

 male with lessened, vitality, for strong arguments may be 

 adduced in favour of such a belief.* Certain curious facts in 

 the natural history of some of our gall-making Cynipidae lend 

 singular weight to these views. From these facts, ascertained 

 by Mr. H. F. Bassett, of Waterbury, Connecticut, there can 

 be little doubt that many of the species produce two distinct 

 kinds of galls, alternating with each other, — the one vernal, 

 the other autumnal. The former produce flies with a due 

 proportion of the sexes, and the latter produce nothing but 

 large females. f In other words, the directly fecundated and 

 more highly vitalized eggs produce nothing but large females, 

 while the parthenogenetic offspring is smaller, and composed 

 of both males and females. 



* See ' American Naturalist,' vi. pp. 093, 747 ; and ' Missouri Entomolo- 

 gical Reports,' iv. p. G5, and v. p. 85. 



+ To give a single illustration: — A large wool-gall, the modification and 

 deformation of a bud, is tolerably common on our black oaks. The liies pro- 

 duced from it (Cyuii^s q. -operator) are bisexual. Mr. Bassett Las witnessed 

 the female depositing in acorns of the same trees on which the wool-galls 

 occur. The product of these eggs is a pip-like gall (C. q.-operatola of my 

 manuscript), which develops between the cupule and the fruit. It is quite 

 irregular in form, but with the apical end tapering more or less to a point, 

 and the basal end rounded. It is gi'eeuish when young, yellowish when 

 mature, and the larva rests in a cream-coloured ovoid cell, easily freed from 

 its pip-like covering. The gall is generally numerous enough to render the 

 acorns abortive, and I have known it since 1800. In August, 1871, while 

 visiting Mr. Bassett, I collected a number from Quercus ilicifolia, and brought 

 them home in the hope of rearing the Hies from them. This spring, after a 

 lapse of about twenty months, and just as the oak-buds were bursting, I suc- 

 ceeded in obtaining a number of ilies, every one of them females, and agreeing 

 with C. q.-operator, except in being larger. Singularly enough this very year 

 IMr. Bassett succeeded, for the first time, in finding the producer of the woolly- 

 gall, C. q.-operator, ovipositing in buds ; and his description leaves no doubt 

 that the flies he thus discovered are identical with my bred specimens. 



