PATHOGENIC SPIRILLA. 



503 



had formed along the line of inoculation settles down as a curled 

 or irregularly bent, yellowish-white thread in the lower part of a 

 slender tube filled with liquefied gelatin, the upper part of which 

 widens out and is continuous with the funnel above. Upon the sur- 

 face of nutrient agar a moist, shining, white layer is formed along 

 the line of inoculation impfstrich. Blood serum is slowly liquefied 

 by this spirillum. Upon the surface of cooked potato, in the incu- 

 bating oven, a rather thin and semi-transparent brown or grayish- 

 brown layer is developed. In bouillon the development is rapid and 

 abundant, especially in the incubating oven ; the fluid is only slightly 



W 



FIG. 178. Cultures in nutrient gelatin, at the room temperature (16 to 18 C.), at the com- 

 mencement of thefourth day; a. Spirillum choleras Asiatic; 6, Spirillum tyrogenum; c, Spirillum 

 of Finkler and Prior. (Baumgarten.) 



clouded, but the spirilla accumulate at the surface, forming a wrin- 

 kled membranous layer. Sterilized milk is also a favorable culture 

 medium. In general this spirillum grows in any liquid containing a 

 small quantity of organic pabulum and having a slightly alkaline 

 reaction. An acid reaction of the culture medium prevents its de- 

 velopment, as a rule, but it has the power of gradually accommo- 

 dating itself to the presence of vegetable acids, and grows upon 

 potatoes in the incubator only which have a slightly acid reaction. 

 Abundant development occurs in bouillon which has been diluted 

 with eight or ten parts of water, and the experiments of Wolffhugel 



