278 



disease among field mice, aud found that to a limited extent 

 the grey rat {3Tus decunianus) was affected b}' it. He then 

 endeavoured to increase the virulence of the bacillus by the 

 process of passing the microbe a certain number of times from 

 rat to rat. In tliis he was disappointed, for while he found 

 the earlier cultures virulent enough to kill the animals in 

 about a week, and the subsequent passage through two or thre^ 

 more rats resulting in a slightly increased virulence, causing 

 death in a little shorter time, the continued passage of the same 

 strain of bacilli through yet more rats always "resulted in a 

 constantly decreasing virulence, so that finally no rats died at 

 all." By careful attention however to the environment of the 

 bacilli themselves while being cultivated, Dr. Dauysz has been 

 able to maintain his cultures for the past eight years in a state 

 of constant high potency, just as Professor Klein, Dr. Clarke, 

 and our Canary fanciers have succeeded in heightening the 

 virulence of the avian septic bacillus by the use of egg. 



The practical outcome of all this "ru1)bisli " is that to-day 

 for a few pence the bird fancier and aviarist can obtain sufficient 

 bacilli in a culture tube to rid his bird-room or aviary of both 

 rats and mice for a period of some months' duration. And he can 

 do this with perfect safet}' to either birds, dogs, or cats, whether 

 these should happen to eat either the inoculated crusts of 

 bread or the bodies of the dead rodents. "In most of the 

 small villages round Odessa it was observed that the rodents 



completely disappeared [after the use of the virus], and 



several weeks afler the operations had been carried out the 

 Bacteriological Institute [of the ' great town of Odessa '] was 

 able to procure only 14 rats alive and in good healtli, although 

 it offered a reward of 15 Kopecks a head." 



I hope to give further particulars in our next issue — 

 especially with regard to the commercial and practical aspect 

 of this question. 



THE WILD CANARY :— According to Cage Birds of the 

 30th ult. four of these charming birds have quite recently been 

 acquired by the Zoological Gardens. Those to whom the 

 Canar}' in its original form is a stranger — and they are many — 

 should take the opportunity of comparing these specimens 

 with the vaiious published descriptions of the species, 

 including that in the Brit. Mus. Cat. Vol. XII. 



W. Geo. CRKSWHiyi.. 



