294 ACTINOMYCOSIS AND ALLIED DISEASES 



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 presum- 

 ably a mere trace of 

 oxygen obtainable (Fig. 

 101). In bouillon, growth 

 takes place at the bottom 

 of the medium in rounded 

 masses which afterwards 

 undergo disintegration. 

 Wright found when the 

 organism was grown in 

 the presence of serum or 

 other animal fluids that 

 the formation of true 

 clubs occurred at the ex- 

 tremity of some of the fila- 

 ments (Fig. 102). From 



the conditions under 

 FIG 100.- Actinomyces, from a culture on which th QC he 



glycerin agar, showing the branching of . . S , 

 the filaments. 1S inclined to regard 



Stained with fuchsin. . x 1000. it as a true parasite, 



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. 

 It is quite evident that further investigations are required in 

 the light of the results detailed. Certainly the parasite in 

 many cases of actinomycosis in the human subject does not 

 grow on ordinary media under aerobic conditions as Bostrom's 

 organism does. 



Varieties of Actinomyces and Allied Forms. It is probable that in 

 the cases of the disease described in the human subject there is more 

 than one variety or species of parasite belonging to the same group. 

 Gasperini has described several varieties of actinomyces bovis according 



