ACTINOMYCES B0VI8. 443 



cept that the colors are fainter. 



Agar Streak. — At first delicate, like dewdrops ; then 

 there slowly forms (after six to ten days) a whitish to 

 whitish-yellow growth with an abruptly scalloped border, 

 faintly lustrous and fairly elevated. This gradually comes 

 to resemble a growth of Mycobacterium lacticola with its 

 elevated paddings and ridges. After a very long time 

 (thirty days) the growth gradually becomes dry, sinks in, 

 and the color changes from white to yellow or brown. 

 The culture appears to grow deeper into the nutrient 

 medium, and often becomes surrounded by a more deli- 

 cate zone, but in our cultures, in distinction to Bostrom' s, 

 no air hyphse and no downy appearance was formed. The 

 water of condensation remained clear. 



Serum Streak Culture (after Bostrom). — At first the 

 colonies are like dewdrops, which first become a little 

 broader and thicker ; then, extending out from some places, 

 a whitish, velvety, dry covering is obtained. While the 

 surface of the colony which is turned toward the serum 

 gradually becomes colored from yellowish-orange to brick- 

 red, — as do the older, puffed portions of the growth, — a 

 delicate border of transparent bristling hairs is formed 

 about the growth, in which later there form anew little but- 

 tons and puffs, which are first whitish and then change to 

 yellowish or reddish. 



Bouillon Culture. — The bouillon remains clear; at the 

 bottom ball-like masses form, which are broken up with 

 difficulty by shaking. Colonies upon the surface were 

 never observed by us and rarely by Afanassiew. Micro- 

 scopically the balls consist of threads with radially 

 arranged fibers. Even in old bouillon cultures we could 

 see no clubs. 



Milk Culture. — Unchanged after eight days. 



Potato Culture. — Slightly knobby, yellowish-white 

 layer, closely attached to the potato, strictly limited to the 

 streak. Often there occur distinct white, or yellow, and, 

 according to Bostrom, also red spots (65, viii). 



Special Nutrient Media. — According to Bostrom, the 

 fungus also grows in non-albuminous nutrient media, and 

 even in sterilized water, as it does in bouillon. In an 



