238 THE HYPHOMYCETES 



In Alkaline or Media deficient in Sugar it grows more in the form of 

 mycelial threads. 



Pathogenesis. Besides being found in infants' mouths, it has also 

 been observed in adults in the oesophagus, middle-ear, trachea, and in 

 both nasal cavities in a young man after a severe attack of influenza. 

 Pathogenic for rabbits when inoculated intravenously, the fungus be- 

 coming localized in the internal organs. 



OIDIUM LACTIS. 



Found in sour milk, on bread, and decayed fruit. On cream the 

 colonies can be recognised by transmitted light as faintly yellow 

 round spots. 



Microscopical Appearances. Single mycelial threads give oft 

 cylindrical joints like yeast-cells (oidien), which towards their extremities 

 become gradually shorter, resembling conidia. The mycelium consists 

 of septate branched threads of various thickness. (For Photomicrograph 

 of this fungus, see Fig. 89). 



Staining Reactions. Stains easily with the ordinary aniline stains ; 

 but dried specimens, owing to the heating in their preparation, cause 

 shrinking and alteration in the form of the oidien. 



Biological Characters. It grows well on all kinds of nutrient 

 media, especially when the reaction is slightly acid, at both room and 

 incubator temperature. The optimum temperature is 15 to 20 C. 



On Gelatine Plates a white, long, hairy, mycelial growth develops, 

 which covers the plate but does not liquefy the medium. 



On Agar the growth at first is delicate, but later a viscous yellowish- 

 white coating forms. 



On Potatoes, a whitish growth. 



On Milk a skin is formed on the surface. 



Sugar is fermented and Albuminoids decomposed. 



Non-pathogenic. 



PENICILLIUM GLAUCUM. 



This fungus is of universal occurrence. It is found on jam, cheese, 

 decaying fruit, and on barley when it is lying on the malt-house 

 floor. It also occurs on the walls and ceilings of rooms. In the 

 young stage it consists of whitish tufts, which later acquires a green 

 colour, due to the formation of myriads of spores. The free spores 

 are covered externally with a fatty layer which protects them from 

 moisture. 



Microscopical Appearances. A mycelium is formed from which 



