152 EXPERIMENT STATION RECORD. 



The various species of tlie genus have widely different local habitats, some 

 inhabiting woodland, others swamps and watercourses, others open upland 

 prairies, and others rocks, cliffs, and arid desert regions. Even single species 

 are said to live under a surprising diversity of conditions. All are habitually 

 nocturnal, though occasionally individuals under unusual circumstances may be 

 seen abroad l)y day. Many of them doubtless burrow to some extent, but in most 

 cases those that live underground occupy natural openings or retreats formed 

 by other animals. They do not hibernate, but remain active throughout the 

 winter even in northern latitudes. 



Although the food habits of various species are not quite the same, in general 

 it may be said that very few feed extensively upon green and succulent food, 

 such as is taken by the meadow mice, but nearly all prefer dry food, especially 

 seeds and small nuts. Nearly all the species readily enter buildings in search 

 of food and finding an easy living make themselves permanently at home. On 

 the whole, they are less injurious to agricultural interests than meadow mice, 

 but nevertheless they are vermin and their i7ndue increase should be checked. 

 This can be accomplished best by trapping and poisoning as in the case of 

 meadow mice. 



On the paratyphyoid and food-poisoning bacilli, and on the nature and 

 efl3.ciency of certain rat viruses, F. A. Bainbridge {Jour, Path, and Bact., IS 

 (1909), Xo. .'i, j)P- .'I'iS-.'iGG). — "The viruses examined owe their potency to one 

 or other of two bacilli which are indistinguishable from B. acrtryck or B. 

 cnteritidis resjiectively. 



" Under the conditions of the experiments, namely, the provision for the rats 

 of abundant sjiace, food, and shelter, the destructive power of the viruses was 

 inconstant; the death-rate in different experiments varying from 20 to 50 per 

 cent. 



" Experiments made with phosphorus paste under similar conditions caused 

 a higher and more uniform mortality than did any of the viruses, the death- 

 rate varying from 61 to 67 per cent. 



" There is reason to believe that a certain proportion of the rats fed on the 

 virus become immune, and would therefore be unlikely to succumb to a second 

 infection. 



"The statements of the entire innocence of the viruses for man require 

 justification." 



A bibliography of 28 titles is appended. 



The bacillus of the comniercial product " ratin " as a means for extermi- 

 nating- rats, Xylander (Arb. K. Gsndhtsamt., 28 (1908), No. 1, pp. 1^5-167; 

 abs. in Bui. Inst. Pasteur, 6 (1908), Xo. 17, pp. 786-788). — Details are here 

 presented of the cultural and bacteriological characters of the "ratin" bacillus 

 and of feeding experiments therewith. Under the most favorable circumstances 

 no per cent of the wild rats remain immune to its action, this being due probably 

 to old infections with the Giirtner group. 



Some reflections regarding the free use of bacteriological cultures for the 

 destruction of rats and mice, J. Danysz (Brit. Med. Joior., 1909, No. 2508, 

 pp. 209, 210). — The author here considers the possible source of danger to man 

 from the use in the destruction of rodents and other small mammals of certain 

 nncrobic cultures that belong to the Salmonella or Bacillus cnteritidis group. 



According to the most recent investigations two types are to be distinguished 

 among these bacilli, first, those to which belong the l)acillus of LoefHer, that of 

 hog cholera, and that of psittacosis, all apparently identical with B. paratyphus 

 B, and second, those to which belong the bacilli of the viruses of Danysz, Is- 

 satschenko, Neumann, and Dunbar, which seem to be identical with the B. 

 cnteritidis of Gaertuer. While the microbes of the Salmonella group are 



