478 FOOD REQUIREMENTS 



1930, 1933a, 1936) have been grown under comparable conditions; 

 other parasitic flagellates (M. Lwoff, 1929a, 1929b, 1929c, 1929d, 

 1933a, 1933b, 1937, 1938a; Glaser and Coria, 1935b; Cailleau, 1936a, 

 1936b, 1937a, 1937b, 1938a, 1938b) apparently require, in addition, 

 blood, serum, tissue extracts, or special growth factors. 



Photoautotrophic Nutrition 



Photoautotrophic nutrition is generally attributed to the chlorophyll- 

 bearing plant-like flagellates and is, by definition, limited to this group 

 of Protozoa. On the other hand, there is no evidence to support the as- 

 sumption that all chlorophyll-bearing species are photoautotrophic, since 

 several green flagellates have been grown only in amino acid or peptone 

 media. Furthermore, in the absence of pure cultures, there is no conclu- 

 sive evidence that any member of the Chrysomonadida, Heterochlorida, 

 Cryptomonadida, Dinoflagellida, or Chloromonadida is capable of carry- 

 ing on photoautotrophic nutrition. While it may be expected that such 

 flagellates will be found in each of these orders, speculation must re- 

 main subject to experimental verification. 



The known facultative photoautotrophs are: Chlamydomonas agloe- 

 formJs (M. Lwoff and A. Lwoff, 1929), Chlorogonium elongatum 

 (Loefer, 1934), C. euchlorum (Loefer, 1934; Hall and Schoenborn, 

 1938a), Haematcoccus pluvidh (M. Lwoff and A. Lwoff, 1929), and 

 Lobomonas piriformis (Osterud, 1938, 1939), representing the Phyto- 

 monadida; and Euglena anabaena (Dusi, 1933b; Hall, 1938b), E. graci- 

 lis (Pringsheim, 1912; Dusi, 1933a; Hall and Schoenborn, 1939a), 

 E. klebsii and E. stellata (Dusi, 1933b) and E. viridis (Hall, 1939a), 

 representing the Euglenidae, 



The establishment of autotrophic strains has often encountered diffi- 

 culties, and conflicting results have sometimes been reported for the same 

 species. Some of the apparent contradictions may be the result of differ- 

 ences in culture media and in technique. In addition, the technical diffi- 

 culties may sometimes be augmented by a selective action of inorganic 

 media, as observed in Etiglena (Hall and Schoenborn, 1938b). 



The present knowledge of food requirements in photoautotrophic 

 nutrition is far from complete. In fact, it is not yet possible to list all 

 the elements which are essential to growth, and little or nothing is known 

 about quantitative food requirements. However, the following elements. 



