BACTERIA IN WATER 57 



it is difficult to gauge this exactly. The flagella are terminal 

 and lateral, and are elastic and wavy. Their active con- 

 traction produces an evident current in the field of the 

 microscope. 



Cultures. This organism may be isolated from ulcerated 

 Peyer's patches in the intestine, from the liver, the spleen, 

 and the mesenteric glands. Owing to the mixture of bacteria 

 found elsewhere, it is generally best to isolate it from the 

 spleen. The whole spleen is removed, and a portion of its 

 capsule seared with a hot iron to destroy superficial organ- 

 isms. With a sterilised knife a small cut is made into the 

 substance of the organ, and by means of a sterilised platinum 

 wire a little of the pulp is removed and traced over the sur- 

 face of agar. Agar reveals a growth in about twenty-four 

 hours at 37 C., which is the favourite temperature. A grey- 

 ish, moist, irregular growth appears, but it is invariably at- 

 tached to the track of the inoculating needle. On gelatine 

 the growth is much the same, but its irregular edge is, if any- 

 thing, more apparent. There is no liquefaction and no gas 

 formation. On plates of gelatine the colonies appear large 

 and spreading, with jagged edges. The whole colony ap- 

 pears raised and almost limpet-shaped, with delicate lines 

 passing over its surface. There is an appearance under a low 

 power of transparent iridescence. The growth on potato is 

 termed " invisible," and is of the nature of a potato-coloured 

 pellicle, which looks moist, and may at a late stage become 

 a light brown in colour, particularly if the potato is alkaline. 

 Milk is a favourable medium, and is rendered slightly acid. 

 No coagulation takes place. Broth is rendered turbid. 



Micro-pathology. Typhoid fever is an infiltration and co- 

 agulation, necrosis, and ulceration of the Peyer's patches in 

 the small intestine of man. The mesenteric glands show the 

 same features, except that there is no ulceration. The spleen 

 is enlarged, and contains the germs of the disease in almost 

 a pure culture. The bacillus is present in the intestinal con- 



