1919] ECONOMIC ZOOLOGY — ENTOMOLOGY. 255 



black duck, analyses wviv made of tlir contents of 4S stomachs collected from 

 November to April ami representing all the usual haunts of the species. The 

 amount of animal matter In Its die! amounted to 40.5 per cent, thus exceeding 

 the proportion taken by the black duck by approximately 16 per cent. 



Identifications made of the animal and vegetable food In the stomachs of the 

 three species are reported upon in tabular form. 



The hawks of the Canadian Prairie Provinces in their relation to agricul- 

 ture. P. A. Tatebnkb (Canada l>ci>t. Mines, Geol. Survey, Mus. Bui. 28 (1918), 

 pp. llf, pis. J/, figs. 7).— A popular account. 



Cause of the " fishy " flavor of the flesh of wild ducks, W. L. McAtee 

 (Auk, SS (1918), No. .',, pp. .>,7>,->,76). 



Injurious insects and useful birds, F. L. Washburn (Philadelphia and Lon- 

 don: J. Ji. Lippincott Co., 1918, pp. XVI 11+458, pis. 4, figs. 414). — This work Is 

 intended to serve as a textbook and guide to the successful control of farm 

 pests. 



Report on agricultural damage by vermin and birds in the Counties of 

 Norfolk and Oxfordshire in 1916, It. T. Gunther (London: Oxford Univ. 

 Press, 1917. pp. 92; rev. in Nature [London], 101 (1918), No. 2525, p. 48).— A 

 report of studies made under the auspices of the Oxford School of Rural 

 Economy. 



The wonders of instinct, .7. H. Fabre, trans, by A. Teixeira de Mattos and 

 B. Miall (London: T. Fisher I'nicin, Ltd., 1918, pp. 320, pis. 16). — A transla- 

 tion from the French of cba piers on the psychology of insects. 



The polyhedral virus of insects with a theoretical consideration of filter- 

 able viruses generally, R. \V. Glaskr (Science, n. ser., 48 (1918), No. 1238, pp. 

 301, 302). — These data supplement the account previously noted (E. S. R., 37, 

 p. 253). 



A summary is given of the chief characteristics of the wilt virus based upon 

 material obtained from diseased gipsy moth, army worm, and tent caterpillars. 

 The virus, which has not been cultivated, passes through Berkefeld N but not 

 through Pasteur-Chamberland niters. On examination with the ultramicro- 

 scope there was nothing visible that could be interpreted as being different 

 from minute protein or pigment particles. The virus is destroyed at 60° C. in 

 20 minutes when suspended in water, and by dry heat at 70 to 80° in 20 

 minutes. 1^ resists drying at room temperature for a period of 2 years; 98 

 per cent glycerin for G months; when dry, direct sunlight for 12 hours; and 

 putrefaction for an indefinite time. It is destroyed by 80 per cent alcohol in 

 15 minutes and by 5 per cent carbolic acid in 3 weeks. There is no growth or 

 fermentation of the virus on 1 per cent sugar solutions; no growth or reduction 

 on methylene blue and sodium nitrate solutions ; and no growth or liquefaction 

 on gelatin and casein. 



Experiments on the extrusion of polar filaments of cnidesporidian spores, 

 R. Kudo (Jour. Parasitology, 4 (1918), No. 4, pp. 141-147).— > 'A concentrated 

 solution of hydrogen peroxid is the most perfect and convenient reagent for 

 producing extrusion of the polar filament from spores of Nosema bombycis and 

 of some Myxosporidia in the fresh stale. The action of hydrogen peroxid is 

 accelerated by the presence of weak alkalis. Ringer's solution emulsion is 

 more favorable for filament extrusion than water emulsion. The action of 

 hydrogen peroxid in extruding the polar filament is less effective upon spores 

 which have been desiccated at room temperature than upon fresh ones. Spores 

 dried on a slide for three days do not extrude the filament. The pressure 

 method gives, generally speaking, the same results as the perhydrol method, 

 except that it produces fewer examples of extruded filament. A spore emul- 



