Mastigophora 55 



these investigators, as well as our general experience in the maintenance 

 of stock cultures, indicate that simple media, containing one of the Difco 

 peptones (tryptone particularly), are altogether suitable for growth of 

 the four species mentioned. Other investigators have previously used 

 more complex media for Colpidium and Glaucoma, but it seems that, ex- 

 cept in special cases, little is to be gained by the use of complex salt 

 solutions in addition to peptone. Occasionally, however, such simple 

 media may fail to support growth of the ciliate; Glaser and Coria ( 1935) 

 have recently confirmed their earlier reports that a special medium is 

 necessary for growth of Paramecium whereas a relatively simple medium 

 is suitable for Chilodon and Trichoda. Some of the simpler formulae, 

 which have been tried in our laboratory and found satisfactory, are listed 

 in table 3. 



Medium K was used by Lwoff ( 1929) in his earlier work with Glaucoma 

 piriformis. Although the medium was very satisfactory, Lwoff later 

 concluded that such a complex medium is unnecessary and accordingly 

 substituted medium L (Lwoff, 1932) in his later investigations. Medium 

 M was used by Elliott (1935, 1935a) for Colpidium striatum and C. 

 campylum. Difco tryptone was found to be superior to a number of other 

 commercial peptones, although Difco proteose-peptone and neopeptone 

 were fairly satisfactory. Tryptone gave best results with Colpidium in 

 concentrations of 1.0-3.0%. Johnson (1936) has found that a 1.5% 

 trjrptone medium is optimal for growth of Glaucoma ficaria, while Loefer 

 (1936a) has found it necessary to reduce the concentration to 0.5% for 

 Paramecium bursaria. Formula N was devised by Pringsheim (1928) 

 for P. bursaria. In Loefer's (1936a) experience, the addition of Difco 

 tryptone (0.5%) or better, Difco proteose-peptone (0.5%), results in a 

 medium very satisfactory for the growth of this ciliate in bacteria-free 

 cultures. Medium O was made up by Loefer (1936a) on the basis of 

 tap water analyses, since it had been found that tap water (New York 

 City) gave excellent results in the cultivation of several species of Pro- 

 tozoa. Either tryptone or proteose-peptone is added to the salt solution 

 in a concentration of 0.5%. Medium P was used for Paramecium bur- 

 saria by Pringsheim (1928, p. 310) ; with tryptone or proteose-peptone 

 added, fhis formula gives a medium satisfactory for growth of the species 

 in bacteria-free culture. 



For another medium which has given good results with several bacteria- 

 free strains of ciliates, the reader is referred to the work of Glaser and 

 Coria (1935). Since this medium requires blood serum in its prepara- 

 tion, it will be less generally useful than the simpler media described 

 above, but it should be quite useful in laboratories in which the necessary 

 technical facilities are available. 



