600 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



animal is killed by them, and the protection they confer is complete, 

 whilst they preserve their properties for several months, and are as 

 effectual with oxen as with sheep. 



Cultivation of the virus of other diseases is equally modified by 

 compressed oxygen, as is notably that of swine fever (rouget). 



In conclusion, the author trusts that this method of attenuating 

 virus, as yet only tried on a small scale in laboratory experiments, 

 may be rendered generally available in practice, with the immense 

 advantages it offers of (1) immunity conferred by a single inoculation, 

 with (2) perfect safety, and (3) the possibility of using the modified 

 cultivations a considerable time after their preparation. 



Rabies.* — L. Pasteur, with the assistance of MM. Chamberland 

 and Eoux, has a further f communication on this important subject. 



1. If rabic virus is passed from a dog to a monkey, and then from 

 one to other monkeys, it gradually becomes weaker. If it is then 

 injected into a dog, rabbit, or guinea-pig, it remains in this attenuated 

 condition. 



2. The virulence of the poison is increased when it is passed 

 from rabbit to rabbit, or from guinea-pig to guinea-pig. If in this 

 " exalted " condition it is passed on to a dog it gives a rabies which is 

 always mortal in effect. 



3. Although one can thus increase the virulence of the poison 

 by passing it from one to another rabbit, it is necessary to do so 

 several times if one is making use of a virus which has been attenuated 

 by a monkey. 



Thanks to these observations Pasteur has been able to preserve 

 an organism from the effects of more active virus by the use of 

 that which is less so. Here is an example: — Virus, made more 

 powerful by passage through several rabbits, is inoculated into a dog, 

 but as it is inoculated into the dog at every stage of the experiments 

 on the rabbits, the result is that the dog becomes entirely refractory 

 to the poison of rabies. 



Pasteur proposes to make the following experiments, of which the 

 first is the most decisive. He will take twenty of his " refractory " 

 dogs and twenty that have not been inoculated ; he will let all be 

 bitten by a " mad dog," and he prophesies that his twenty will escape 

 the effects, while the other twenty will exhibit the influences of the 

 poison. A similar set of two twenties will be trepanned by the virus 

 of dogs a rage des rues ; the twenty vaccinated dogs will resist the 

 poison, the others will die, either mad or paralysed. In a footnote 

 the author points out that of the twenty non-vaccinated dogs, or, as he 

 calls them, witnesses, all will not exhibit the effects of the poison to the 

 same extent, for rabies does not always follow on the bite of a mad dog. 



Bacteria in Canals and Rivers.J — The much-discussed question as 

 to the purification of water in rivers " by itself," that is, by the mere 



* Comptes Rendus, xcviii. (1884) pp. 1229-31. 

 t See this Journal, ante, p. 430. 

 j Nature, xxix. (1884) p. 557. 



