596 PATHOGENIC SPIRILLA. 
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 
ly slightly 
Fia. 178.—Cultures in nutrient gelatin, at the room temperature (16° to 18° C.), at the com- 
mencement of the fourth dey; a, Spirillum choleree Asiatice; b, Spirillum tyrogenum; ¢, 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 aceommo- 
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 Wolffhiigel 
