PROPERTIES OF THE BACTERIOPHAGE 303 



protective action is still more marked with acetone, the coagulating 

 action is still more energetic and the antiseptic action is correspondingly 

 less.* 



In this connection, I might remark that all authors state that by- 

 reagents of this type the bacteriophage is first precipitated and then 

 destroyed. This conclusion is of significance not only in connection 

 with this particular experiment but in the case of aU substances which 

 coagulate proteins. Inasmuch as the corpuscles are always found in 

 suspension in liquids which contain protein materials (even in the case 

 where the culture medium is synthetic, for the dissolved bacterial sub- 

 stance is present) we can not tell whether the corpuscles are precipitated 

 directly as such or whether they are carried down mechanically enclosed 

 by the precipitate which forms in the medium. That the corpuscles 

 as such may be precipitated is possible, even probable, but as yet we can 

 not prove it. 



Acetone. If we add 0.25 cc. of an undiluted suspension of the bacterio- 

 phage to 5 cc. of acetone we find that a destruction of the corpuscles 

 occurs, — after 15 days for a Staphylo-bacteriophage, after 25 days for a 

 Shiga-bacteriophage. 



If this experiment is repeated, except that the acetone is combined 

 with the same bacteriophage when diluted 1 : 1000 with slightly alkaUne 

 distilled waiter it is found that the destruction of both races of the 

 bacteriophage is complete after 3 days. 



Chloroform. I have found that when a suspension of Shiga- or 

 Staphylo-bacteriophage is kept over a layer of chloroform a very definite 

 attenuation may be noted even after 3^ hours. 



Essences. The corpuscles maintain their virulence unimpaired when 

 held for 8 days in media saturated with essence of thyme, or essence of 

 cloves (d'HereUe^^O- 



Phenol. The bacteriophage (Shiga) is destroyed after contact for 7 

 days with 1 per cent phenol (d'Herelle^^O • In a 10 per cent solution 

 of this antiseptic it is destroyed in less than 24 hours. Watanabe*^^^ 

 has observed that the rapidity of destruction by phenol depends, in some 

 measure, upon the race of bacteriophage tested. Acting over a period 

 of 24 hours, a 1 per cent solution destroyed some races, while with other 

 races it required a 2.5 per cent solution, or even a 4 per cent solution, 

 to exert the same effect. 



* On several occasions I have observed a curious fact, namely, that bottles of 

 acetone were contaminated by B. subtilis, whose spores appeared to resist the 

 action of this substance for a long time. 



