A. D. Tmms 
81 
of the latter can be confidently recommended to the agriculturalist 
In this country, the best work so far prosecuted on insecticides, is the 
series of experiments carried out at the Woburn Experimental Fruit 
Farm (Duke of Bedford and Pickering, 1906, 1908 and 1909). 
3. Deterrants may be defined as poisons usually of a milder 
nature than contact or stomach poisons, and not necessarily insecticidal 
in their action. Crops are sprayed with these agents in order to render 
them nauseous, with the result that they are saved from insect depreda¬ 
tions, the insects being compelled to seek other pabula. 
IV. Economic Entomology. 
The term “ economic ” entomology I propose to restrict to its 
narrowest sense namely, with reference to those insects destructive 
to stored and manufactured goods. Under this heading we have all 
insects injurious to grain, flour, nuts, seeds and other dry food-stuffs. 
Insects attacking woollen goods, carpets, furs, leathers and hides ; also 
those species injurious to paper, books, stored timber and furniture ; 
insects attacking cheese, hams, tobacco, dried fruits, vinegar, drugs and 
museum specimens. In short this branch of the subject might be 
defined as commercial and domestic entomology. The possibility of 
the utilization of the X-rays in connection with this branch of the 
subject has not so far been adequately tested. Forel and Dufour sub¬ 
jected ants to the Rontgen rays, but they exhibited no tendency towards 
being affected thereby, and no after-effects were detected eight days 
after the experiments had been discontinued. Axenfeldt experimented 
with houseflies, and concluded that they can perceive the X-rays, and 
that the latter affect them in much the same way as ordinary light. 
Hunter (1912, p. 188), in America, subjected insects in various stages 
of development to the action of the X-rays, but no effects were detected 
upon the fertility or the development of the species used. In his 
experiments special attention was directed toward the determination of 
the question whether the sexual organs of insects are affected in any 
manner analogous to that in the case of mammals, but the results gave 
an entirely negative answer. In April of last year, Morgan and Runner 
(1913, p. 226) published records of a careful series of experiments 
on the effect of the X-rays on the cigarette beetle, giving full details 
of the methods employed. The results, however, were also entirely 
negative ; the subsequent behaviour of the insects was in every way 
identical with that of the untried individuals used as controls. In 
Parasitology vii 
6 
