484 FOOD REQUIREMENTS 



tion, a few of the chlorophyll-bearing species have been maintained in 

 darkness in such media (Jahn, 1935c, 1935d; A. Lwoff and Dusi, 1929, 

 1931, 1935a, 1935b; M. Lwoff and A. Lwoff, 1929; Loefer, 1934; 

 Provasoli, 1938b), especially with added acetate. Certain Trypanosomi- 

 dae, such as Strigomonas oncopelti, have been grown in peptone media 

 (M. Lwoff, 1930, 1933a, 1936), but growth of other Trypanosomidae 

 (M. Lwoff, 1929a, 1929b, 1929c, 1929d, 1933a, 1933b) and of Polymas- 

 tigida (Glaser and Coria, 1935b; Cailleau, 1935, 1936a, 1936b, 1937a, 

 1937b, 1938a, 1938b, 1939) seems to be supported only by more complex 

 organic media containing blood, serum, tissue extracts, or particular 

 growth factors. Several of the ciliates — Colpidium campylum and C. 

 striatum (Elliott, 1933, 1935b), Glaucoma ficaria (D. F. Johnson, 

 1935a), G. piriformis (Lwoff, 1924, 1925, 1929a), Paramecium bursaria 

 (Loefer, 1934b, 1936b, 1936c), and certain Sarcodina — Acanthamoeha 

 castellanii (Cailleau, 1933, 1934), Mayorella palestinensis (Reich, 1935, 

 1936), have been grown in peptone media comparable to those which 

 support growth of the heterometatrophic Phytomastigophora. On the 

 other hand, Glaser and Coria (1930, 1933, 1935a) have used somewhat 

 more complex media for several free-living ciliates. 



At present little is known of the nitrogen requirements in heterometa- 

 trophic nutrition, and definite conclusions regarding the saprophilic or 

 saprogenic nature of particular species are not always possible. Enzymes 

 which hydrolyze gelatin and casein are produced by C. striatum (Elliott, 

 1933), by G. piriformis (A. Lwoff and Roukhelman, 1929; Lawrie, 

 1937), and by Saprophilus oviformis, Trichoda pura, and Chilodon 

 cucullus (Glaser and Coria, 1935a); hence these ciliates cannot be con- 

 sidered saprophilic organisms. A. Lwoff" (1924, 1925) found that com- 

 plete peptones were satisfactory for growth of G. piriformis, whereas silk 

 peptone, gelatin, and fibrin, each supposedly lacking certain amino acids, 

 were inadequate. Recently, however, several strains of C. campylum have 

 been grown in the writer's laboratory for twenty-four transfers in silk 

 peptone media and for eighteen transfers in gelatin media. In a compari- 

 son of various peptones, Elliott (1935b) noted that C. striatum and C. 

 campylum grew most rapidly in the peptones containing high percentages 

 of free amino N. and Van Slyke amino N. Growth of the same ciliates 

 (Hall and Elliott, 1935) was also accelerated by certain amino acids, 

 added singly to a medium which supports slow multiplication. As in 



