CULTIVATION OF ACTINOMYCES 



335 



anaerobe and in ceasing to grow at a temperature a little below 

 that of the body. Under ordinary aerobic conditions either no 

 growth occurs or it is of a very slight character. On the surface 

 of agar under anaerobic conditions the organism produces dense 

 rounded colonies of greyish- white colour, which sometimes 

 assume a rosette form. A somewhat curious feature of growth 

 is described by Wright, namely, that in a shake culture in 

 glucose agar the colonies are most numerous and form a dense 

 zone about half an inch from the surface of the medium, that 

 is, at a level where there 

 is presumably a mere 

 trace of oxygen obtain- 

 able (Fig. 100). In 

 bouillon, growth takes 

 place at the bottom of 

 the medium in rounded 

 masses which afterwards 

 undergo disintegration. 

 Wright found that, when 

 the organism was grown 

 in the presence of serum 

 or other animal fluids, 

 the formation of true 

 clubs occurred at the 

 extremity of some of 

 the filaments (Fig. 101). FlG 

 From the conditions 

 under which growth 

 occurs, he is inclined to 

 regard it as a true para- 

 site, and doubts whether it can have a saprophytic existence 

 outside the body, e.g., on grain. He is also of opinion that 

 all cases of true actinomycosis, i.e., cases where colonies visible 

 to the naked eye are present, are probably produced by one 

 species, and that the aerobic organisms obtained by Bostrom and 

 others are probably accidental contaminations. There is thus no 

 doubt that the parasite in many cases of actinomycosis in the 

 human subject does not grow on ordinary media under aerobic 

 conditions as Bostro'm's organism does. 



The views of Wright are supported by the recent observations 

 of Harbitz and Grondahl on actinomycosis in Norway. They 

 obtained pure cultures from ten different cases, and in each 

 instance the organism grew only under anaerobic conditions and 

 presented the characters described above. They also obtained 



. Actinomyces, from a culture on 

 glycerin agar, showing the branching of the 

 filaments. See also Plate III., Fig. 10. 



Stained with fuchsin. x 1000. 



