482 FOOD REQUIREMENTS 



tained in darkness (heteromesotrophic and heterometatrophic nutrition), 

 as described below. 



Hutner (1936) failed to note acceleration of growth by fatty acids 

 or carbohydrates in E. anabaena or by carbohydrates in E. gracilis. Since 

 Hutner's conclusions apparently were based upon the macroscopic ap- 

 pearance of his cultures, he may have overlooked effects comparable to 

 those reported by other workers. 



Heteroautotrophic Nutrition 



The utilization of inorganic nitrogen compounds in the presence of 

 acetate or another organic carbon source, has been attributed to several 

 colorless Phytomastigophora : Chilomonas Paramecium (Mast and Pace, 

 1933), Polytoma uvella (Pringsheim, 1921; Lwoff and Dusi, 1938a), 

 P. ohtiisum (Lwoff, 1929b, 1932), and y^j/^ji^ sp. (Schoenborn, 1938, 

 1940) . The results of Mast and Pace have not been duplicated by Loefer 

 (1934) nor by Hall and Loefer (1936). Pringsheim (1935a) reported 

 growth of C. Paramecium in an ammonium-salt and acetate medium, but 

 Lwoff and Lederer (1935) and Pringsheim (1935b) have pointed out 

 that Pringsheim's medium contained "extract of soil," without which 

 the flagellates failed to grow. Hence, Pringsheim did not confirm the 

 observations of Mast and Pace. More recently, Lwoff and Dusi (1937a, 

 1938a, 1939b) have grown a strain of this species in an ammonium 

 acetate medium, but only in the presence of either thiamine or thiazole 

 and pyrimidine. Since Lwoff and Dusi added organic nitrogen com- 

 pounds to their medium, application of the term heteroautotrophic to C. 

 Paramecium may be inappropriate. The contradictory results obtained 

 by various workers with this species have not yet been explained. It is 

 possible that different strains may vary in their nutritional requirements. 

 Or it is conceivable that the strain of Mast and Pace was established 

 through a selective process, similar to that reported in several species 

 of Euglena (Hall and Schoenborn, 1938b). 



The first known instance of heteroautotrophic nutrition in Euglenida 

 is that described by Schoenborn (1938, 1940) in Astasia sp. This strain 

 has now passed the nineteenth transfer, so that the peptone carried over 

 from the original stock culture has been reduced, through serial dilu- 

 tion alone, to a calculated concentration of less than 1.8 X 10^^^ gm. 

 per cc. 



According to Pringsheim (1937b), Chlorogoyjium euchlorum may be 



