/l/ According to E. G. Pringshelm, the organism used in these studies was E. genicuXata. /?/ According to E. G. Prlng- 

 Bheim, the organism used In these studies was E. mutabllis. /}/ Syn. A. chattonl (A. Lwoff, 1956) or A. klebsll (H. von 

 Dacb, I9UO). /U/ A generic term including cyancobalaml n (vitamin Bj^g) and its hydrogenatlon product (known variously as 

 Bi2a or Big^,) which has approximately the same biological activity. /5/ It has been reported that the organism requires 

 no vitamins, but it is possible that this comes about only after adaptation to vitamin-less media, as with other species of 

 Euglena. /6/ The organism utilizes also pseudo-cobalamin. /?/ Can be replaced by pyrlmidine. /8/ Can be replaced by 

 pyrlmidlne and thiazole. /9/ Can be replaced by thlazole. /lO/ Negative results reported for organic acids may not be 

 significant since it has been shown that Prototheca zopfii and Euglena gracilis utilize them only at pH 5.5 5-5. Most of 

 the negative results tabulated were obtained in media having a pH near neutrality, /ll/ Utilized only at pH 5. 0-5-5. 

 /12/ Optimal concentrations are similar to those of the corresponding fatty acid (cf. Fn lU). /I5/ Inadequate for growth 

 in a mineral medium. /lU/ The average range of concentration, in grams p<r 100 ml of media, at which fatty acids are uti- 

 lized and non-toxic Is the following: acetic, propionic, butyric and Isobutyrlc acids, 0.1-0.2; valeric and isovaleric 

 acids, O.O5-O.I; caprolc, isocaproic, heptylic and octyllc acids, 0.01-0.05; nonyllc acid, 0.01; decyclic acid, 0.005- 

 0.006. Some of the negative results tabulated may be Incorrect if toxic concentrations were employed. In general, 

 toxicity increosea with the length of the chain of carbon atoms and with Ihe decrease in the pH of the medium. 



34 



