BACILLI IN CHRONIC INFECTIOUS DISEASES. 477 
serum. The growth at the end of fourteen days is more abundant than 
upon blood serum at the end of several weeks. When numerous 
bacilli have been distributed over the surface of the culture medium 
a rather uniform, thick, white layer, which subsequently acquires a 
yellowish tint, is developed ; when the bacilli 
are few in number or are associated in scattered 
groups separate colonies are developed, which 
acquire considerable thickness and have more 
or less irregular outlines; they are white at 
first, then yellowish-white. Frankel describes 
the tubercle bacillus as a facultative anaérobic, 
and it would appear that it must be able to grow 
in situations where it can obtain very little oxy- 
gen from its development in the interior of tu- 
berculous nodules, lymphatic glands, etc. But 
in stick cultures in glycerin-agar development 
only occurs near the surface, and not at all in 
the deeper portion of the medium. In view of 
its abundant growth on the surface it is diffi- 
cult to understand this failure to grow along 
the line of puncture, if it is in truth a faculta- 
tive anaérobic. 7 
In peptonized veal broth containing five per 
cent of glycerin the bacillus develops at first in 
the form of little floceuli, which accumulate at 
the bottom of the flask and which by agitation 
are easily broken up. At the end of two or 
three weeks the bottom of the flask is covered 
with similar flocculi, which form an abundant 
deposit. 
Pawlowski and others report success in cul- 
tivating the tubercle bacillus upon the surface 
of cooked potato enclosed in a test tube after 5, 18 culture of tu. 
the method of Bolton and Roux. The open end __ vercle bacillus upon glyce- 
of the tube is hermetically sealed in a flame che Photograph by 
after the bacilli have been planted upon the 
obliquely-cut surface of the potato; this prevents drying. Ac- 
cording to Pawlowski, better results are obtained if the surface of 
the potato is moistened with a five-per-cent solution of glycerin. The 
growth is said to be seen at the end of about twelve days as grayish, 
dry-looking flakes ; at the end of three or four weeks it forms a dry, 
smooth, whitish layer, and no further development occurs. 
The range of temperature at which this bacillus will grow is 
very restricted ; 37° C. is usually given as the most favorable point, 
