23« THE AMERICAN MONTHLY [Aug., 



(carbonized vaccines). The living vaccines possess a greater 

 vaccinating power, but the carbonized vaccines have the ad- 

 vantage in being perfectly safe to handle or to leave about. 

 They do not appear to be impaired by keeping, and could be 

 sent out from some central place where they could be made in 

 quantity. 



The attenuated cultures are obtained by M. Haff kine by cul- 

 tivating the cholera bacillus in media which are continually 

 aerated at a temperature of 39° C. When the cholera bacilli 

 have been grown under these unfavorable conditions for some 

 time, they become so weakened that they cause a local oedema 

 instead of necrosis when they are injected into the subcutan- 

 eous tissue of a guinea-pig. Attenuated germ3 can be cultivated 

 indeffinitely in agar tubes without regaining any of their lost 

 virulence. The " exalted " vaccines are obtained by growing 

 the cholera bacilli in the peritoneal cavities of a series of guinea- 

 pigs. As each guinea-pig dies the fluid which is found in the 

 peritoneal cavity is inoculated into a second pig and so on un- 

 til the virus has passed through a series of twenty or thirty an- 

 imals. During such a long series it is very difficult to avoid 

 contamination of the virus unless the strictest care is exercised. 



The cholera bacilli are not sufficiently virulent when in- 

 solated from the intestinal discharge of cholera patients. 



The emulsions are prepared from the attenuated and " exal- 

 ted " cholera bacteria, by mixing the surface growth on agar 

 cultures one day old, with sterilized bouillon, two or three ccm. 

 of liquid for each agar culture. The carbolized vaccines are 

 prepared in precisely the same manner as the others but instead 

 of bouillon, a five per cent solution of carbolic acid is used. 



In these vaccines there are no living cholera germs. The 

 vaccines are injected beneath the skin with a sterilized hypo- 

 dermic syringe. The injection of the "exalted" vaccine is 

 made about five days after the injection of the attenuated virus. 



MEDICAL MICROSCOPY. 



Detection of the Bacillus Tuberculosis.— M. M. Pewsner 

 and NastinkofF, of the bacteriological laboratory of Professor 

 Afanassieff at the Clinical Institute of the Princess Elena Pau- 

 lowna, contribute to Wratch the following process for staining 



