1000 THE HIGHER BACTERIA, MOLDS AND FUNGI 



have proved as satisfactory for diagnosis as the simple treatment with 

 caustic soda. The process of clearing may be hastened by gently heating 

 the slide. 



Cultivation. Cultures may be obtained from the lesions by distributing 

 fragments of the infected epidermis or hairs over the surface of agar slants. 

 Four per cent glucose agar or Sabouraud's test medium mentioned below 

 are suitable for this purpose but cultures can also be obtained on plain agar. 

 The chief difficulty is to avoid overgrowth of the parasites by bacteria and 

 molds. The ordinary plating procedures are inapplicable. Skin fragments 

 may be soaked for a few minutes, and hairs for hours, in 95 per cent alcohol 

 before planting without killing the fungi. Increasing the acidity of the 

 media to P H 5.0 ; adding to it 1 part in 80,000 of methyl violet, or 1-200,000 

 brilliant green are of some assistance. Any of these procedures inhibit the 

 bacteria considerably but they are of little avail against the molds. Main 

 reliance must be placed on making a large number of plants from each case. 



As the gross appearance of the cultures varies greatly with the cultural 

 conditions, Sabouraud has suggested a standard test medmm on which 

 cultures should be planted for the purpose of identification. This has the 

 following composition: 



( Sabouraud 's Test Medium) 



Maltose brute de Chanut 40 gm. 



Peptone granulee de Chassaing 10 gm. 



Distilled water 1000 gm. 



Agar agar 18 gm. 



The mixture is dissolved in the autoclave, filtered through paper, poured 

 into Erlenmeyer flasks to a depth of about 1 cm. and sterilized once in 

 the autoclave, allowing the temperature to rise slowly to 120 degrees. 

 Sabouraud does not define the reaction of the medium and it cannot be 

 exactly reproduced except by employing the brands of reagents which he 

 suggests. It has, however, a reaction of about P H 5.5 and similar though 

 not identical results can be obtained by employing domestic peptone and 

 malt extract and adjusting the reaction to this point. 



In order to prevent the pleomorphic changes in the cultures, Sabouraud 

 recommends that stock strains should be preserved on a medium of the 

 following composition: 



(Habourand 's Conservation Medium) 



Peptone granulee (10 to 50) usually 30 gm. 



Agar agar 18 gm. 



Distilled water 1000 gm. 



