ACTINOMYCES, RAY FUNGUS. Ill 



these authors do not appear to have succeeded in 

 cultivating the fungus on artificial substrata through a 

 long series of generations. Hence we were up till 

 recently entirely without any guide as to the place 

 occupied by the ray fungus in the vegetable kingdom. 

 Lichtheim observed in his investigations on aspergillus 

 and mucor that a stunted mycelium, closely resembling 

 the ray fungus, was at times formed in the animal body ; 

 and this was the only fact, though in truth a very feeble 

 one, on which a relation of actinomyces with the mould 

 fungi was provisionally based. 



Lately Bostrom has made a preliminary communica- Bostrom's 

 tion, from which we seem to be approaching an elucidation l 

 of the behaviour of the ray fungus in cultivations, and of 

 its place in the vegetable world. Bostrom employed for 

 his cultivation experiments not the refracting, club-like 

 processes, which cannot be cultivated, but the central 

 network. The grains were placed in gelatine, which 

 was poured out on plates ; the slow growth of the mass 

 in the gelatine was not however awaited, but after a few 

 days the grains which had remained free from contami- 

 nation were taken out of the gelatine, crushed between 

 glass plates, and then employed for stroke inoculations 

 on ox blood serum and agar. These strokes soon acquire 

 a finely granular, whitish appearance, having become in 

 the first two days broader and thicker ; then there- appear 

 in the centre small yellowish red nodular patches, the 

 borders of which are occupied by extremely delicate, 

 branched processes, growing from the line of inoculation 

 at definite distances. These yellowish red masses become 

 gradually confluent, and covered with a delicate downy 

 white layer ; at the periphery similar masses are subse- 

 quently formed. The cultures require seven to eight 

 days for this stage. The temperature optimum is 

 between 33 and 37 C. The gelatine is not liquefied by 

 the actinomyces. The inoculation of such cultivations 

 on various animals has been repeatedly carried out with 

 positive results by Bostrom. 



Microscopically the cultivations show in the first two 

 days threads with true dichotomous branching. At 



