Toxic Products 593 



taining fish, snails, water-plants, and protozoa, was able to recover 

 it from the water after thirty-six days, and from the mud in the bot- 

 tom after two months. In elaborate experimental studies of this 

 question Jordan, Russel, and Zeit* found its longevity to be only 

 three or four days under conditions resembling as nearly as possible 

 those found in nature. When buried in the upper layers of the soil 

 the bacilli retain their vitality for nearly six months. Robertsonf 

 found that when planted in soil and occasionally fed by pouring 

 bouillon upon the surface, the typhoid bacillus maintained its vitality 

 for twelve months. He suggests that it may do the same in the soil 

 about leaky drains. 



Cold has little effect upon typhoid bacilli, for some can withstand 

 freezing and thawing several times. Observing that epidemics of 

 typhoid fever had never been traced to polluted ice, Sedgwick and 

 Winslowf made some investigations to determine what quantitative 

 reduction might be brought about by freezing, and accordingly ex- 

 perimentally froze a large number of samples of water intentionally 

 infected with large numbers of typhoid bacilli from different sources. 

 It was found that the bacilli disappeared in proportion to the length 

 of time the water was frozen, and that the reduction averaged 99 per 

 cent, in two weeks. The last two or three bacilli per thousand 

 appeared very resistant and sometimes remained alive after twelve 

 weeks. 



They have been found to remain alive upon linen from sixty to 

 seventy-two days, and upon buckskin from eighty to eighty-five 

 days. 



The typhoid bacillus resists the action of chemic agents rather 

 better than most non-sporogenous organisms. The addition of 

 from o.i to 0.2 per cent, of carbolic acid to the culture-media is 

 without effect upon its growth. At one time the tolerance to carbolic 

 acid was thought to be characteristic, but it is now known to be shared 

 by other bacteria (colon bacillus). It is killed by i : 500 bichlorid 

 of mercury solutions and 5 per cent, carbolic acid solutions in five 

 minutes. 



Metabolic Products. The typhoid bacillus does not produce indol. 

 It produces a small amount of acid when grown in sugar-containing 

 media, but its regular tendency is to form alkalies, as is shown by the 

 reactions in litmus milk. It forms no coagulating or proteolytic 

 enzymes. 



Toxic Products. The disproportion of local to constitutional dis- 

 turbance in typhoid fever and the irritative and necrotic charac- 

 ter of its lesions suggest that we have to do with a toxic organism. 

 Brieger and Frankel have, indeed, separated a toxalbumin, which 

 they thought to be the specific poison, from bouillon cultures. When 



* "Journal of Infectious Diseases," 1904, I, p. 641. 



"Brit. Med. Jour.," Jan. 8, 1898. 

 j "Jour. Boston Soc. of Med. Sci.," March 20, 1900, vol. iv, No. 7, p. 181. 



38 



