172 MEDICAL MYCOLOGY 



grow in height and at the periphery and turn brown, becoming contorted and 

 scattered with small white, velvety points, with a white velvety area at the 

 periphery which is festooned. Colonies hard, compact, adherent to the agar. 



On Sabouraud agar moistened with maceration of ganglia, the young 

 colonies appear as on dung agar, the older colonies more folded and yellowish 

 white, sandy, somewhat darker in age. Time of incubation shorter on suc- 

 cessive subcultures (first in 1 month, fifth in 3 weeks, tenth in 10 days). Be- 

 tween the fifth and tenth subcultures, organism is inoculable into ordinary 

 agar, glucose agar, malt agar, with same aspect as on Sabouraud agar, but 

 less abundant and less velvety growth. On carrot and potato, colony elevated, 

 slightly folded, brownish gray, darkening in age, moist, smooth. On g-elatin, 

 white velvety colonies, medium rapidly liquefied. On milk growth very slow, 

 milk coagulated. 



Mycelium produced in the water of condensation of horse or sheep serum 

 with 6% glycerol, horse serum agar, ordinary peptone agar, or glucose bean 

 (2% agar with 20 drops of bean decoction added). The mycelium is oidiform, 

 irregular with chlamydospores. 



While liquid media are not suitable for isolation or early subcultures, 

 growth is possible after a time on peptone (1%) and glucose (5%), if the 

 inoculum is floated on the surface and the culture incubated at 35° C. There 

 is formed a thick whitish pellicle composed of yeast cells, spherical or ovoid, 

 overlying the limpid liquid. Finally mycelium appears in the pellicle. If 

 0.5% agar is added to increase the viscosity, the pellicle is thick, folded, snow 

 white, composed of yeast cells and, especially, thick-walled hyphae similar to 

 those on Sabouraud agar. 



The optimum temperature is 37° C, but the medium dries out too rapidly; 

 growth at this temperature is about twice as fast as at 25-30° C. At the 

 higher temperature, the colonies are softer, more spongy, with more velvet, 

 and not so adherent to the substrate. The maximum temperature is 38-40° 

 and the minimum 15-18° C. At lower temperatures growth is very slow in 

 the early subcultures, becoming more rapid after the organism has become 

 adjusted to artificial media. At room temperatures, the colonies are elevated, 

 folded, white, powdery or velvety, composed of very thin-walled hyphae and 

 some sprout cells. After some weeks, short thick-walled hyphae are seen and 

 the septa are more evident. In liquid media development is very slow at 

 20-25° C. If a culture is removed from 35-36° to 20-25°, it produces a grayish 

 folded pellicle, the yeast cells cease budding and produce slender thin-walled 

 hyphae as on glucose. If the culture is removed from 20-25° to 30-36°, the 

 number of yeast cells increases. In low oxygen tension (under a layer of oil) 

 growth is very slow, large irregular cells 12-15/a in diameter, thick-walled, 

 granular, often in chains of 5-6 cells with large oil globules. Citric acid up 

 to 1 :2,000 favors growth, producing a grayish folded pellicle or small round 

 white colonies floating on or in the medium. Mycelial forms at low tempera- 

 tures similar to those seen in pus. Bierbaum (1919) found slow growth on 

 slightly alkaline horse meat agar with 2% glucose, 2.5% glycerol, and 3-4 c.c. 



