368 PATHOGENIC BACTERIA. 



sin i, and phenol 5. After staining they are washed in 

 distilled water containing i per cent, of acetic acid, 

 dehydrated in alcohol, cleared, and mounted. In such 

 preparations the bacilli may be found in little groups, 

 which are easily discovered, under a low power of 

 the microscope, as reddish specks, and readily resolved 

 into bacilli with the high power of the oil-immersion 

 lens. 



In bacilli stained by this alkaline methylene-blue solu- 

 tion dark-colored dots may sometimes be observed near 

 the ends of the rods. These dots were at first regarded 

 as spores, but are now denominated polar granules, and 

 are thought to be of no importance. 



The typhoid bacillus is both saprophytic and parasitic. 

 It finds abundant conditions in nature for its growth and 

 development, and, enjoying strong resisting powers, can 

 accommodate itself to environment much better than the 

 majority of pathogenic bacteria, and can be found in 

 water, air, soiled clothing, dust, sewage, milk, etc. con- 

 taminated directly or indirectly by the intestinal dis- 

 charges of diseased persons. 



The bacillus is also occasionally present upon green 

 vegetables sprinkled with water containing it, and epi- 

 demics are reported in which the infection was traced to 

 oysters from a certain place where the water was infected 

 through sewage. Newsholme 1 found that in 56 cases 

 of typhoid fever about one-third was attributable to the 

 eating of raw shell-fish. In such cases the evidence 

 accumulated serves to show that the shell-fish were from 

 sewage-polluted beds. The bacillus probably enters milk 

 occasionally in water used to dilute it. 



The resistant powers of the organisms have already 

 been described as great. They can grow well at the 

 room-temperature. The thermal death-point is given by 

 Sternberor as 60 C. The bacilli can, according to Klem- 

 perer and Levy, remain vital for three months in distilled 

 water, though in ordinary water the commoner and more 



1 Brit. Med. Jour., Jan., 1895. 



