120 ESSENTIALS OF BACTERIOLOGY. 



The colon bacillus not only resembles the typhoid germ in 

 form, but also in some of the pathologic processes produced. 

 For points of resemblance and difference, see Bacillus coli com- 

 munis. 



In Water. Bacilli have been found which also resemble ty- 

 phoid bacilli, and one must be very careful not to make any 

 positive statement. 



Examination of Water for Typhoid Bacilli. When a water is 

 supposed to contain typhoid bacilli, 500 c.cm. of the same is 

 mixed with 20 gtt. of |-per cent, carbolic acid, which destroys 

 many of the saprophytes. 



Plates are then made as described under Water Analysis. 



Those colonies which then form and have a tendency to liquefy, 

 are touched on second day with permanganate of potassium, 

 and when so colored, destroyed with bichloride of mercury. 



Those that now develop are transferred by inoculation to fresh 

 plates. At the end of eight days they are examined under 

 microscope ; every colony not possessing motile bacilli is dis- 

 carded. The motile bacilli are tested with Gram's method of 

 staining ; those that do not take the stain are alone retained. 

 Cultures are made from these upon potatoes, and, if the char- 

 acteristic growth occurs, then only can they be called typhoid 

 bacilli with any certainty. 



Pathogenesis. Lower animals have npt yet been given enteric 

 fever, though their death has been caused by injection of the 

 bacilli into the veins of the ear. 



In man it has been found in the urine, blood, sputum, milk, 

 intestinal discharges, roseolar spots, and in various organs, as 

 spleen, liver, lymphatic glands, and intestinal villi. 



It is found in secretions several days after the attack has sub- 

 sided. It is found only in this disease, and regularly. 



Way of Infection. The bacilli in the dejecta of the diseased 

 person find their way into drinking water, milk, or dirty clothes, 

 and so into the alimentary tract of a person predisposed to the 

 disease. They enter the blood through the lymphatics, and so 

 become lodged in various organs. They are quite resistant, liv- 

 ing for some time in the soil and water, and are not affected as 



