ORGANIC NUTRIENTS OF FUNGI 19 



Saprolegnia jerax, and S. monoica to utilize sucrose [Pieters 

 (1915) ] and by the utilization of galactose by Trichophyton inter- 

 digitale [Mosher et al. (1936)] and Aspergillus fischeri [Wenck 

 etal (1935)]. 



Schade's (1940) observations show that Apodachlya brachy- 

 nema grows well on dextrose, levulose, and sucrose but is unable 

 to utilize maltose and galactose, whereas Leptomitus lacteus uses 

 none of these sugars. 



By respirometric methods Wolf and Shoup (1943) noted that 

 Allomyces arlniscula, A. javanicus, A. moniliformis, and A. cysto- 

 genns are able to use dextrin. Allomyces arbuscula uses maltose 

 and sucrose; none utilizes d-arabinose, /-arabinose, cellobiose, glu- 

 cose, galactose, lactose, levulose, mannitol, or starch. 



Certain pathogens possess wide capabilities for utilizing carbo- 

 hydrates, whether mono-, di-, or polysaccharides, as is illustrated 

 by Moore's studies (1937) of Thymatotrichum omnivornm. She 

 determined that this organism uses dextrose, levulose, galactose, 

 maltose, sucrose, lactose, mannite, xylose, inulin, dextrin, starch, 

 glycerin, and cellulose and introduced another factor into the 

 problem by varying the oxygen tension. Decrease in oxygen 

 tension was accomplished by the removal of oxygen with pyro- 

 gallic acid; increase, by the introduction of oxygen from a storage 

 cylinder. Oxygen at normal atmospheric concentration was 

 found optimum for growth. 



Foster et al. (1941) studied the direct utilization of C0 2 by 

 Aspergillus niger and certain other molds. By employing radio- 

 active carbon (C n ), they were able to show that carbon is me- 

 tabolized into cellular material and organic acids. It may achieve 

 a role in respiratory changes connected with the formation of 

 oxaloacetate from pyruvate and C0 2 . The oxaloacetate thus 

 formed may in turn give rise to fumaric acid or to succinic and 

 citric acids. Earlier workers had suggested that C0 2 enters into 

 the metabolism of fungi, but proof was not forthcoming until 

 Foster and his associates made use of labelled carbon. 



Careful consideration, beginning perhaps with von Naegeli's 

 (1880) investigations in 1880, has been given to certain organic 

 acids as sources of carbon. A4uch remains, however, to be accom- 

 plished. The work of Camp (1923) with citric acid serves to il- 

 lustrate the ability of fungi to utilize organic acids. He compared 

 the growth of certain fungi on media containing citrates as a 



