Axenic Cultivation of a Pelagic Diatom 123 



and the diatoms was considered. 



The following complex defined medium supported good 

 growth in bacterized cultures, of Chaetoceros dydimus, Asterion- 

 ella japonica and a species of Coscinodiscus (Table 1). 



TABLE 1 

 Medium For Growth of Diatoms 



NaCl 



MgCL 



Na2S04 



CaCl. 



KCl 



NaHCOs 



KBr 



Na^SiOa 



KNOa 

 K;HP04 



K-glycerophosphate 



H3BO. 



FeCl3 



NaF 



LiNO^ 



MnCh 



ZnSO^ 



KI 



NaaMoOi 



CoCU 



CuSO, 



EDTA 

 TRIS 



Re-distill. H.O 



20 gr 

 4.5 gr 

 3.5 gr 

 1.0 gr 

 600 mg 

 40 mg 

 60 mg 

 20 mg 



200 mg 



35 mg 



1 mg 



6mg 



2mg 



1 mg 



200 meg 



100 meg 



50 meg 



50 meg 



10 meg 



10 meg 



5 meg 



10 mg 



500 mg 

 1000 ml 



Adenine 100 meg 



Uraeil 100 meg 



Xanthine 100 meg 



Thiamine 30 meg 



Choline 10 meg 



Nicotinic acid 5 meg 



P-amino benzoic ac. 2 meg 



Pyridoxine 1 meg 



Riboflavin 1 meg 



Biotin 1 meg 



Folic acid 0.1 meg 



B,. 0.1 meg 



Ca pantothenate 300 meg 



Inositol 500 meg 



L-ascorbic acid 200 meg 



Citric acid 20 meg 



Aspartic acid 25 meg 



Beta-alanine 15 meg 



Glutamic acid 15 meg 



Glycine 15 meg 



1-Ieueine 10 meg 



Histidine 10 meg 



Serine 10 meg 



Tryptophane 5 meg 



Cystine 5 meg 



Methionine 3 meg 



While realizing that a great number of the organic substances 

 included in the mediimi may not be required, it was thought 

 that a complex medium offered better chances of success, and 

 could be later dissected. The concentrations of the various growth 

 factors proved adequate, and non-toxic, if not required. 



This medium, without TRIS, was sterilized at first by filtra- 

 tion through an UF glass filter, then, after addition of TRIS at 



