760 EXPERIMENT STATION RECORD. [Vol. 38 



ECONOMIC ZOOLOGY— ENTOMOLOGY. 



Review of the grizzly and big brown bears of North America (genus 

 Ursus), with description of a new genus, Vetularctos, C. H. Mebriam (17. S. 

 Dept. Agr., Bur. Biol. Survey, North American Fauna No. Jfl {1918), pp. 136, 

 pis. 16). — lu the present review the author describes 19 new species and 4 

 new subspecies and erects the new genus Vetularctos, of which V. inopinatus 

 n. sp., the patriarchial bear, is the type. A total of 86 forms of the grizzly 

 and big brown bears are recognized. 



The rat as a carrier of Spirochaeta icterohaemorrhagiae, the causative 

 agent of Weil's disease (spirochsetosis icterohaemorrhagica), Y. Ido, R. Hoki, 

 H. ITO, and H. Wani (Jour. Expt. Med., 26 (1917), No. 3, pp. Sftl-353) .—The 

 author's findings, here reported, led to the conclusion that the extermination 

 of rats and field mice is a highly important prophylactic measure against Weil's 

 disease. 



" The chemical composition of soil and water plays an important part in the 

 development of S. icterohoeinorrhagioE and consequently in the spread of the 

 disease of which it is a causative agent." 



Animal parasites of rats at Madison, Wis., A. M. Moix (Jour. Parasi- 

 tology, 4 {1917), No. 2, pp. 89, 90). — In an examination of 25 rats captured in 

 different parts of Madison, Wis., 53 per cent were found to be parasitized by 

 fleas, 60 per cent by lice, 12 per cent by mites, 88 per cent by intestinal round- 

 worms, 4 per cent by trichinae, and 20 per cent by the dwarf tapeworm {Hy- 

 menolepis diminuta). 



Investigations of the value of nitrobenzol as a parasiticide, with notes 

 on its use in collecting external parasites, W. L. Chandleb {Jour. Parasi- 

 tology, 4 {1917), No. 1, pp. 27-32). — This is a brief report of investigations 

 conducted to determine the action of nitrobenzol upon various animals when 

 such animals are exposed to the vapor of this drug at various temperatures 

 and for various periods of time. 



The results show that it is impossible to predict jiist what effect any given 

 condition of exposure to the vapor will have on an animal. The fact that it 

 is impossible to kill either fleas or biting lice by any condition of exposure 

 under that corresponding to 26° C. (78.8° F.) for six hours makes it clearly 

 evident that this drug can not be used with any degree of safety in the fumi- 

 gation of animals to destroy their external parasites. 



Since it seems hardly probable that one hom-'s exposure to the vapor of 

 nitrobenzol at temperatures between 20 and 25° C. (68 and 77° F.) will seri- 

 ously affect any of the domesticated animals and fleas and biting lice become 

 stupified after an hour's exposure at the same temperatures and are shaken 

 off by the host in great quantities, it is quite possible that nitrobenzol fumi- 

 gation may be used to good advantage in collecting specimens of external 

 parasites. 



A study of the toxicity of kerosene, W. Moobe and S. A. Graham {Jour. 

 Econ. ErU., 11 {1918), No. 1, pp. 70-75). — "Kerosene varies greatly in its physi- 

 cal characteristics and its chemical composition, even when coming from the 

 same oil field. Low boiling point fractions of kerosene are in general more 

 toxic to plants than high boiling point fractions when used pure. Injury by 

 fractions with low boiling points can largely be prevented if they are applied to 

 the form of an emulsion, since the emulsion holds the oil away from tlie plant 

 until such time as it has evaporated. Emulsification of high boiling point 

 fractions does not give this protection since the oil remains on the leaf after the 

 emulsion is destroyed. Low boiling point fractions are more toxic to insects 

 in the form of vapor than high boiling point fractions due to the slight vola- 



