ACTINOMYCOSIS. 361 



and Israel, has been cultivated by Bostrom, Affanassieff, 

 and others. This second variety of actinomyces grows 

 more energetically in the presence than in the absence of 

 air an important differential diagnostic point in relation 

 to that already described. The temperature-optimum is 

 37 C. (98.6 F.), although the fungus will grow well also 

 at ordinary room-temperature. Upon gelatin-plates, and 

 still better upon agar-plates, there form at first fine, radiat- 

 ing colonies, which develop with comparative activity to 

 opaque nodules, whose periphery presents a delicate fila- 

 mentous network. In agar streak-culture a continuous 

 deposit does not form, as a rule, but a series of more or 

 less closely approximated nodules. The latter not rarely 

 exhibit a brick-red color upon blood-serum, and become 

 covered by a whitish, down-like coating consisting of air- 

 hyphae. From these there develop, through a process of 

 segmentation, a series of roundish bodies arranged like 

 chains, the so-called actinomyces-spores. These are de- 

 stroyed only after exposure- for five minutes to a tempera- 

 ture of 75 C. (167 F.), whereas the mature forms die at 

 as low a temperature as 60 C. (140 F.). When kept in 

 the thermostat for some time, a wrinkled, coherent mem- 

 brane eventually develops upon blood-serum, while the 

 nutrient medium is softened. Upon potato the aerobic 

 actinomyces grows as a brick-red deposit, and likewise with 

 air-hyphae. In bouillon floating and in part granular mem- 

 branes form that sink to the bottom, while the overlying 

 fluid remains clear. Milk is gradually peptonized. 



With regard to the microscopic appearances, the granules 

 and the druses, which constitute the characteristic feature of 

 the morbid process from which the aerobic actinomyces is 

 obtained, resemble in every detail those already described, 

 so that it is only necessary to refer to the account of these. 

 Preparations made from pure cultures, however, display great 

 differences. Long filaments with rectangular branches may 

 be seen that have arisen through the process of budding. 

 Terminal enlargements are encountered but rarely in old 

 colonies that have developed in the depth of the culture- 

 media. Transmission of the aerobic ray-fungus to animals 

 has not yet been effected with certainty a third point in con- 

 tradistinction from the anaerobic species of Wolff and Israel. 



With regard to the botanic position of the actinomy- 

 ces, it was formerly included among the pleomorphic bac- 



