660 THE PARASITIC HYPOMYCETES 



Glycerin-agar. Growth appears after 2 days and takes the form of small, 

 yellowish-white, dry, wrinkled colonies, firmly adherent to the medium. The 

 colonies soon become confluent and form a broad, yellowish, 

 wrinkled band, covered with rough projections. 



Gelatin. Discomyces bovis grows feebly on gelatin. 

 Liquefaction takes place slowly and to a very slight extent. 

 On plates, after incubating for about 6 days, small, greyish, 

 punctiform colonies appear with yellow centres and irregular 

 outline. 



Potato. After about a week or rather less, small colourless 

 colonies appear ; a few of these soon become greyish and 

 prominent then the growth thickens and forms a yellowish, 

 wrinkled, mammillated layer sometimes edged with black. 

 The potato turns brown in the neighbourhood of the 

 growth. 



Milk. Milk is not coagulated. 



Cultures on seeds. On fresh grains of corn or dry seeds 

 softened in water Discomyces bovis grows as a yellowish, 

 powdery layer and penetrates into the interior of the seed. 



3. Biological properties. 



Vitality. Discomyces bovis is fairly resistant to heat arid 

 other destructive agents. Cultures are killed by exposure 

 to a temperature of 70-75 C. for 10 minutes (Wolff), 

 ^ n . Cultures on dried-up agar or gelatin live for more than a 



IG. oil. DlSCO- _^ \ _ V ,. . , /.. -i 



myces bovis. Culture year. Poncet found the parasite alive in culture alter being 

 week g )! ycerin agar (1 neglected for four years. Ordinary antiseptics appear to 

 have little effect on the organism : but on the other hand, 

 1 drop of a 1 per cent, solution of methylene blue added to 10 c.c. of a broth 

 culture sterilizes the latter. 



Virulence. The virulence of Discomyces bovis is attenuated by passage 

 through the tissues of man and some of the lower animals. Its vegetative 

 and pathogenic properties can be restored by growing it on vegetable tissues 

 (Liebmann). A plant which grew from a seed inoculated with Discomyces 

 bovis, was found to be infected, the parasite taking the form of very short 

 filaments, and these were pathogenic on inoculation into animals (Liebmann). 



Toxins. Filtered glycerin-broth cultures of Discomyces bovis contain a 

 toxin (Streptothricine, Delearde) which, like tuberculin, has very little effect 

 on healthy animals, but in infected animals gives rise to a febrile reaction. 



Association with other micro-organisms. In the tissues, Discomyces bovis 

 is frequently found in association with other organisms, most frequently with 

 the more common organisms of suppuration, and occasionally in pulmonary 

 lesions with the tubercle bacillus. Sputum in which the Discomyces has been 

 found should always be examined for the tubercle bacillus. 



The parasites of actinomycosis. 



"^Recent investigations would tend to show that the clinical condition of actino- 

 mycosis is not a specific disease but may be due either to Discomyces bovis or to one 

 of several other parasites which though differing from are all more or less related to 

 it. Some cases of actinomycosis, for instance, have been shown to be due to Dis- 

 comyces asteroides (vide infra] which has been found by several observers in human 

 lesions. [Discomyces liquefaciens and Discomyces garteni (vide infra) have also been 

 isolated from cases of the disease. ] 



Ferre and Fajuel, Scheele and Petruschky, have described cases of actinomycosis 



