62 MEDICAL MYCOLOGY 



diagnosis, at least to a genus name, and seems puzzled if the mycologist 

 promptly reports that he has a species of Monilia and 2 or 3 months later 

 changes his report to Zymonema. 



Among the true yeasts, several methods are in vogue, none of which is 

 uniformly successful, but all of which may sometimes produce results. All 

 should be tried before placing an unknown organism in the large and poorly 

 defined genus Cryptococcus. Stelling-Dekker (1931) has summarized these 

 methods and in most cases traced the method to the original author. The 

 oldest method is that of Engel (1872), popularized by Hansen (1883), where 

 the cells from an actively growing colony are scraped off and placed on a 

 sterile block of plaster of Paris (gypsum) which is kept moist by sterile water, 

 or malt extract (Klocker 1924) or by mannitol-phosphate solution (18 c.c. 

 2% mannitol + 2 c.c. 5% dipotassium phosphate) (Saito 1923). Gorodkova 

 (1908) reported the use of an agar rich in nitrogen and poor in carbohydrate 

 which usually bears her name. Distilled water 1000 c.c, agar 10 gm.,* peptone 

 10 gm.,* beef extract 10 gm., sodium chloride 5 gm., and glucose 2.5 gm. 

 Various French authors, notably Guilliermond, have advocated the use of 

 slices of carrot or potato. Beijerinck(1898) advocated the use of plain agar 

 to which no nutrient had been added and which had been thoroughly washed 

 to remove impurities which might possibly be a source of food. 



Wagner (1928) has made a more thorough study of conditions initiating 

 ascospore formation. He emphasizes the importance of the sugars previously 

 used in cultivating the organism and the hydrogen ion concentration of the 

 medium. Kufferath (1928) attributes the success of his medium to its alka- 

 linity. He prepares it as follows : Malt meal is hydrolyzed with sulphuric acid, 

 the acid neutralized with calcium carbonate, and the agar added. It is then 

 brought to the desired alkalinity with sodium hydroxide. In 1930 he studied 

 the matter further. He found that in general the usual concentration of 

 gelatin (15%) is as successful as higher concentrations. He studied the effect 

 of alkalinity and found it rather more successful than acidity in producing 

 ascospores, but occasionally the reverse is true. Before one can be certain 

 that spores are not formed, one should try all the methods. 



Fennentation. — Another character to which some authors have attached 

 much importance in some groups is ability to ferment or to utilize certain 

 sugars. The term "fermentation" is used very loosely by various writers. 

 Some, as Stelling-Dekker, would practically restrict it to the production of 

 alcohol and carbon dioxide from a hexose, while Castellani would include all 

 cases in which acid or gas appears in a carbohydrate-containing medium on 

 which an organism has developed. It is probable that this different use of 

 the term has occasioned much difference of opinion in regard to the fermenta- 

 tive ability of a species. A further source of error is almost inherent in the 

 methods in ordinary use, each of which indicates an equilibrium of several 

 possible reactions, hence it is important to state clearly what method was used 



•Maneval (1924) recommends the omission of peptone, addition of 15 or 20 gm. agar, and 

 reduces Liebig's meat extract to 3 gm. 



