Nutritional Characteristics of Some Chrysornonads 119 



sucrose, glucose, glycerol, propylene glycol, monacetin, diacetin, 

 and N-acetyl glutamate. A large growth response was elicited 

 by the utilized carbon sources for Hymenomonas and Pavlova, 

 much less by Syracosphaera and Ochrosphaera (Table 2). Growth 

 of C. huxleyi was stimulated, but only slightly, by acetate, gluta- 

 mate, pyruvate, acetyl glutamate, sucrose and propylene glycol. 

 Lactate and pyruvate were good C sources for Hymenomonas; 

 acetate and to a less extent glycerol for Pavlova; lactate and to 

 a lesser degree glycerol for Syracosphaera; propylene glycol and 

 to a lesser extent glycine for Ochrosphaera. Leucine is stimula- 

 tory for Hymenomonas: malic, sucrose and acetyl-glutamate for 

 Ochrosphaera. Lactate in high concenti^ation elicits a six to eight 

 fold growth increase of Hymenomonas in light but it does not 

 substitute for photosynthesis: no growth was obtained in darkness. 

 No attempts at growth in darkness have yet been done with the 

 other heterotrophic species. 



DISCUSSION AND CONCLUSIONS 



In exploring the heterotrophic abilities of a few chryso- 

 monads and to elicit significant differences, we used concentra- 

 tion levels far above any likely to be found even in coastal pol- 

 luted waters. The data therefore serve only to determine the 

 \'ersatility of the organisms; one might then make better guesses 

 as to their behavior in nature. For instance, it would be logical 

 to postulate that most of the oceanic forms like Coccolithtis 

 huxleyi would show stenohalinity and that littoral organisms 

 would in general be more euryhaline. From tliis postulate, and 

 from the apparent higher content in organics of littoral 

 waters, one might be tempted to see whether the euryhaline 

 fomis (presumably littoral) are more heterotrophic than the 

 stenohalines, preferring a relatively higher salinity. Indeed the 

 euryhaline Hymenomonas and Syracosphaera can utilize the wid- 

 est range of organic N and C sovn-ces and the stenohaline 

 Coccolithus has very poor heterotrophic abilities. But the eury- 

 haline Pavlova, though responsive to some organic sources of 

 Ochrosphaera utilizes a few organic nitrogen sources and is stimu- 

 carl:)on, cannot utilize any organic N sources, and the stenohaline 

 lated by several C sources. With such a limited sampling one 



