FOOD REQUIREMENTS 485 



Colpidium, Loefer (1936c) found for P. b/asarja that the least satisfac- 

 tory of several peptones were those containing the smallest amounts of 

 amino N. Hence preliminary partial hydrolysis of peptones appears to 

 be advantageous, especially in the early growth of ciliate populations. 



Nitrogen metabolism of G. piriformis has been investigated by 

 A. Lwoff and Roukhelman (1929), who have traced the quantitative 

 changes in total N, peptone N, amino N, ammonia N, and amide N. In 

 Witte peptone medium, peptone N decreased steadily. Amino N in- 

 creased for the first two weeks, and then gradually decreased for two or 

 three weeks; later, a secondary increase sometimes followed the death of 

 many ciliates. Somewhat comparable results have been reported for 

 Acanthamoeha castellanii (Cailleau, 1934), although hydrolysis was 

 always less extensive than in cultures of G. piriformis and much less 

 ammonia N was produced. 



Fermentation of carbohydrates and the acceleration of growth by carbo- 

 hydrates and other carbon sources have been reported in many species. 

 Colas-Belcour and A. Lwoff (1925) observed fermentation of dextrose 

 and levulose by Leptomonas ctenocephali, Leishmnnia tropica, and L. 

 donovani (var. infantum^. More recently, M. Lwoff (1936) has reported 

 fermentation of fourteen carbohydrates by Strigomonas muscidarum and 

 of a smaller number by 5". media and 5". parva. These three flagellates 

 showed specific differences in their fermentation reactions. Likewise, 

 Cailleau (1937b) has described fermentation of several monosaccharides 

 and disaccharides by Eutrichomastix colubrorum, and the fermentation of 

 dextrin, starch, and inulin, as well as some of the simpler carbohydrates, 

 by Trichomonas foetus and T. columhae. Utilization of dextrose by try- 

 panosomes (for review, see von Brand, 1938) has been known for some 

 years. Recently, utilization of dextrose by T. foetus — the strain of Glaser 

 and Coria (1935b) — has been measured by Andrews and von Brand 

 (1938), who found that rate of utilization was correlated with growth 

 rate. Although growth of C. Paramecium is accelerated by dextrose (Loe- 

 fer, 1935a), utihzation of the sugar could not be detected (Loefer, 

 1938b) by means of Benedict's colorimetric method. Acceleration of 

 growth by starch has been reported for Polytoma caudatum (A. Lwoff 

 and Provasoli, 1935), P. obtusum (A. Lwoff and Provasoli, 1937), and 

 Polytomella agilis (A. Lwoff, 1935b). 



Few observations have been reported for the Sarcodina. Fermentation 



