TYPHOID FEVER. 369 



vigorous saprophytes outgrow them and cause their dis- 

 appearance in a few days. When buried in the upper 

 layers of the soil the bacilli retain their vitality for nearly 

 six months. Robertson l 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 connection with leaky drains. 



Cold has no effect upon typhoid bacilli, for freezing 

 and thawing several times are without injury to them. 

 They have been found to remain alive upon linen for 

 from sixty to seventy-two days, and upon buckskin for 

 from eighty to eighty-five days. Sternberg has succeeded 

 in keeping hermetically sealed bouillon cultures alive for 

 more than a year. In the experience of the author, un- 

 less transplanted rather frequently, cultures upon agar- 

 agar are apt to die out. In the presence of chemical 

 agents the bacillus is also able to retain its vitality, o. i 

 to o. 2 per cent, of carbolic acid added to the culture- 

 media being 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. The bacilli seem to be killed in a short time 

 by thorough drying. 



The bacillus is best secured in pure culture, either 

 from an enlarged lymphatic gland or from the splenic 

 pulp of a case of typhoid. To secure the bacillus in this 

 way the autopsy should be made as soon after death as 

 possible, lest the Bacillus coli invade the tissue. 



Cultures of the typhoid bacillus may be obtained, but 

 with difficulty, from the alvine discharges of typhoid 

 patients. In examining this material, however, it must 

 be remembered that the bacilli are certain to be present 

 only in the second and third weeks. 



As numerous saprophytic bacteria are present in the 

 feces, the resistance which the typhoid bacillus exhibits 

 to carbolic acid can be made use of in obtaining the pure 



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

 24 



