BACTERIOLOGY. 183 



thrive well in water. Their resistance to all germicides 

 has been spoken of already. They grow well at 

 room temperature, and boiling in water kills them, 

 since they are killed at the temperature of 60 degrees C. 

 This brings to mind another well-known fact, that the 

 people in certain large cities are requested to boil all 

 the drinking water before it is used. We know the rea- 

 son why such a course is taken when we know the 

 death-point of the germ. Cold has no effect on the 

 germ, and certain chemicals must be very strong be- 

 fore they will kill them. The best chemicals are bi- 

 chloride of mercury and carbolic acid. The bacilli are 

 killed in a short time by drying. So a hot-air steril- 

 izer will be all right for sterilizing the vessels used 

 in the work on this kind of bacteria. 



The best method of obtaining the typhoid germs is 

 to take the animal after it is dead and get the germs 

 from the spleen and lymphatic gland; but you can get 

 them from the dejecta of the patient with difficulty. 



The bacilli are sure to be present in the patient after 

 the second or third week. Right here is the place to 

 try Widal's Test. 



The method of making a pure-culture from a pa- 

 tient's f eces is as follows : Take several tubes of gela- 

 tin and melt the gelatin ; have 10 c.c. of the medium in 

 each tube; now add to each tube i-io c.c. of carboi- 



