PHYSIOLOGY 97 



monas 'Paramecium mentioned above, others appear to be capable of 

 synthesizing it as in Polytoma uvella (Lwoff and Dusi). In a number 

 of ciliates such as Colpidium campylum, C. striatum, Tetrahymena 

 geleii, etc., thiamine seems to support growth according to several 

 workers. For example, Elliott (1939) observed crystalline thiamine 

 chloride to be a limiting factor for the growth of Colpidium striatum 

 in media free from this substance. Vitamin Bi was found most effec- 

 tive in concentration of 1 : 10,000 to 1 : 10,000,000. This worker further 

 found that crystalline riboflavin and vitamin Be (concentrate) cannot 

 supplant thiamine in the nutrition of this ciliate. According to Hall 

 and Shottenfeld (1941), the density of population in bacteria-free 

 cultures of Glaucoma pyriformis is related quantitatively to the con- 

 centration of thiamine and the phases of death also are influenced 

 markedly by the available concentration of this vitamin. For Col- 

 pidium campylum, Hall (1942) observed thiamine and riboflavin to 

 be essential for growth in a de-ashed gelatin medium, and thiamine 

 to be necessary for growth in a silk-peptone culture which has been 

 subjected to prolonged heating in strongly alkaline .solution. 



Lilly (1942) succeeded in growing bacteria-free several strains of 

 Stylonychia pustulata and Pleurotricha lanceolata on ciliates (5 spe- 

 cies), flagellates (3 species) and a strain of Saccharomyces cerevisiae, 

 all cultured in sterile condition. He found that for continued growth 

 of the two ciliates, it was necessary to supply in addition to the food 

 organisms, a supplementary growth factor which was found in the 

 largest quantity in yeast cells and less so in infusions of a wide vari- 

 ety of plant materials, but which was not found in effective concen- 

 trations in media made from animal organs or tissues. This substance 

 was soluble in water and in 70 per cent alcohol, was stable to heat and 

 alkali, and was adsorbed on charcoal and on Fuller's earth. The in- 

 vestigator considers it as not identical with any of the known vita- 

 mins of the B complex. Johnson and Baker (1943) have examined 

 certain B vitamins in relation to populations of Tetrahymena geleii 

 and found: (1) the addition of thiamine to fresh proteose-peptone 

 medium produced a higher maximum population; (2) all of the long- 

 time cultures containing added thiamine, had secondary increase in 

 population, almost to the original peaks, after 64 days; (3) cultures 

 with a mixture of thiamine, riboflavin, and pyridoxine, maintained 

 the highest level of living population; and (4) cultures with para- 

 aminobenzoic acid had higher maximum populations than those ob- 

 tained under other conditions, but died out sooner than the other 

 types of cultures (addition of thiamine prevented this early dying- 

 out). 



