Mastigophora 53 



their chlorophyll throughout the period of culture. The same medium 

 has been used for Haematococcus pluvialis, Colacium vesiculosum, and 

 five species of Euglena, in the maintenance of stock cultures in light. 

 Medium C at pH 7.0 supports good growth of Euglena gracilis, according 

 to the findings of Dusi (1930) and results obtained in our own laboratory. 

 Ammonium phosphate or ammonium sulphate may be substituted for 

 ammonium nitrate. Medium D is the formula used by Lwoff and Lwoff 

 (1929) for Chlamydomonas agloejormis and Haematococcus pluvialis 

 and by Lwoff and Dusi (1929) for Euglena gracilis in darkness, except 

 that Difco tryptone is substituted for the peptone used by the French in- 

 vestigators. In our laboratory, this medium has given excellent results 

 with stock cultures of six species of Euglenida, Haematococcus pluvialis, 

 and two species of Chlorogonium. Medium E was used by Jahn (1931) 

 for Euglena gracilis and by Hall (1933) for E. anabaena and E. deses. In 

 addition, the medium is satisfactory for other species of Euglena, and for 

 Haematococcus and Chlorogonium. Growth is less abundant than in 

 media containing sodium acetate, but the cultures remain viable for 

 several months. Medium F, at pH 7.0, supports good growth of 

 Chlorogonium elongatum, C. euchlorum, and Haematococcus pluvialis. 

 The same medium supports slow growth of the colorless Chilomonas Para- 

 mecium, as reported by Mast and Pace (1933) and confirmed in our 

 laboratory. 



In addition to the various liquid media, certain types of solid media 

 have proved useful in our laboratory, particularly for the growth of stock 

 cultures over long periods and also in the preparation of cultures for 

 shipment. In the preparation of a solid medium we have added either 

 Difco dehydrated dextrose-agar or starch agar to one of the media listed 

 above; for a semi-solid medium, one-half or less of the usual amount of 

 dehydrated agar is added to the liquid. Such media may be tubed and 

 then slanted or not, as preferred. Slant or stab cultures may be sealed 

 with melted paraffin, and will usually remain healthy for several months. 



MEDIA FOR COLORLESS FLAGELLATES 



In general, the addition of peptone in suitable amounts to one of the 

 media (A-F) listed above will provide a satisfactory medium for growth 

 of the colorless Phytomastigophora. The formulae have been varied 

 somewhat by different workers, however, as indicated in Table 2. 



Medium G was used by Pringsheim (1921) for growth of Polytoma 

 uvella, and good results were obtained also by Lwoff ( 1932 ) . The same 

 solution, in Pringsheim's laboratory, was made the base of an agar medium 

 which supported good growth of Polytoma. Medium H is a gelatin 

 medium developed by Lwoff (1932) for Polytoma uvella; with the omis- 

 sion of gelatin, the same formula gives a very satisfactory liquid medium 



