286 BACILLI OF THE TYPHOID GROUP 



mucosa of the small intestine, where it causes local pathologic changes, 

 such as swelling and ulceration of the solitary and agminated lymph 

 follicles, and general symptoms due to the absorption of its toxins. 

 At a later stage it enters the general circulation, becomes localized in 

 the spleen and also in other places, preferably in the lungs, and is 

 then excreted not merely with the feces, but also with the urine, 

 sputum, etc. It is difficult to isolate the bacillus from the feces, less 

 difficult from the urine, and easiest from the juice of the spleen, 

 provided it is obtained in a perfectly aseptic manner. As a rule, 

 typhoid bacilli disappear from the urine and feces within a few 

 weeks after the termination of the disease; they generally, how- 

 ever, remain present for a long time in the gall-bladder. In excep- 

 tional cases persons who have had typhoid fever may void the 

 bacilli with their feces for years, becoming in this way a constant 

 source of spreading typhoid through contaminating milk or water. 

 One attack of typhoid fever, as a rule, induces immunity for the 

 remainder of the individual's life, but in about 2 per cent, of the cases 

 a second attack, generally of a mild character, has occurred. Oysters 

 obtained from water contaminated by sewage may harbor virulent 

 typhoid bacilli, and when eaten raw, cause infection. 



The Typhoid Culture Medium of Drigalski and Conradi. From a 

 hygienic standpoint it is sometimes of great importance to be able to 

 decide whether drinking water, milk, oysters, etc., or the stool of a 

 supposed permanent typhoid carrier contain typhoid bacilli, and in 

 order to find them rapidly a special medium is required. This is 

 prepared as follows : Three pounds of chopped lean beef are allowed 

 to stand with two liters of water in the cold (ice-box in summer) for 

 twenty-four hours. The meat infusion is then boiled for one hour and 

 filtered. Add 20 grams of Witte's dry peptone, 30 grams of nutrose, 

 and 10 grams of common salt; boil another hour; filter again. Now 

 add 60 grams of agar, boil several hours, neutralize with caustic soda 

 solution, and filter clear in the steam sterilizer or hot-water funnel. 

 Take 300 c.c. Kahlbaum's litmus solution, add 30 grams lactose, and 

 boil for fifteen minutes. Mix the fluid agar with the litmus-lactose 

 solution (the mixture will generally turn red); it is now faintly alkalin- 

 ized with a 10 per cent, soda solution. Finally, add 4 c.c. hot sterile 

 10 per cent, soda solution and 30 c.c. of a sterile solution (1 to 1000) 

 of crystal violet (Hoeschst B). This medium is distributed into 

 sterile test-tubes. When the search for typhoid bacilli is made, plates 

 are poured into Petri dishes from the melted medium, and after the 

 latter has set, the surface is inoculated from the suspected material. 

 If the latter is a stool, it must be diluted with nine times its volume 

 of 0.85 salt solution. The plates are then inverted and allowed to 

 stand slightly open for one-half hour to permit the surface to dry 

 somewhat. They are then placed in an inverted position in the 

 incubator and examined after sixteen to twenty-four hours, when the 

 typhoid bacilli, if such have been present, appear as small, transparent 



