664 THE PARASITIC HYPOMYCETES 



which adhere to the sides of the flask while others fall to the bottom. After 

 3 weeks' growth these flakes have attained the size of a green pea : some turn 

 brown in the centre ; others, on the sides of the flask or on the surface of the 

 medium, become pink or red in colour after a month or two. The liquid never 

 becomes cloudy, but the surface is often covered with a white efflorescence 

 formed by the spores. 



Meat broth. The growth on this medium is very scanty. After incubating 

 for a fortnight, small, rounded, greyish granules are formed, the liquid 

 remaining clear. After sub-culturing several times in broth the growth 

 becomes more abundant. 



Gelatin. In ordinary gelatin a very scanty white growth forms along the 

 line of the stab and on the surface of the medium. Growth is more abundant 

 in the following medium : 



Potato, or hay, infusion (vide ante), - - 100 c.c. 



Gelatin, - - 9 grams. 



Glycerin, - 4 ,, 



Glucose, ... 4 ,, 



Neutralize. Sterilize. 



Discomyces madurce does not liquefy gelatin. 



Glucose-glycerin-agar. Ordinary agar is not at all a suitable medium for 

 the cultivation of the parasite, but on glucose-glycerin-agar it grows freely. 

 The culture on the latter medium consists of circular, smooth, raised colonies 

 yellowish-white at first, becoming pink and even bright red later, though the 

 colour eventually disappears. When the colonies do not coalesce they 

 become very large and umbilicated, the central depression being white while 

 the raised margins are reddish. 



Potato. After incubating for 5 days at 37 C. small whitish projections 

 are seen, and these later assume a mulberry-like appearance. Around the 

 growth the potato is depressed, but it does not change colour. When incu- 

 bated for a month the colonies are pale pink in colour and in places the colour 

 deepens and ultimately becomes bright red, orange or deep red. The more 

 acid the potato the more intense the colour. Some of the colonies appear 

 powdered with a fine whitish dust which consists of spores. Some potatoes 

 are unsuitable for the growth of the organism. 



Milk. Growth takes places without coagulation of the medium. 



Serum. Egg. No growth takes place on these media. 



3. Biological properties. All attempts to inoculate animals have failed 

 (Vincent and Nocard). 



Discomyces madurce is very resistant to drying ; cultures dried on sterile 

 blotting paper for 9 months have subsequently given a growth when sown 

 on culture media. A culture on potato 21 months old was still alive. Non- 

 spore-bearing cultures are killed in from 3-5 minutes at a temperature of 

 60 C. Spores resist a temperature of 75 C. for 5 minutes but are killed in 

 3 minutes at a temperature of 85 C. 



Associated micro-organisms. In suppurating nodules opening externally 

 Vincent found besides the Discomyces, Staphylococcus aureus and S. albus. 



X. DISCOMYCES FREERI. 



Syn. Streptothrix freeri. 



[This parasite was found by Musgrave and Clegg in a mycetoma of the 

 foot in a native woman in Manilla. 



[It grows freely on artificial media but only under aerobic conditions. 



