486 FOOD REQUIREMENTS 



of carbohydrates by Acayithamoeha castellanii was not observed by Cail- 

 leau (1933), who also obtained no evidence that sugars are actually con- 

 sumed by this species. On the other hand, dextrose accelerates growth 

 of Mayorella palestinensis (Reich, 1936), maximal effects being pro- 

 duced by concentrations of 0.5 to 1.0 percent. 



In Colpidium campylum and Glaucoma piriformis, Loefer (1938b) 

 has measured dextrose consumption over a short pH range. In general, 

 the rate of utilization followed the growth-pH relationship. Fermenta- 

 tion of carbohydrates has been demonstrated previously in several species. 

 G. piriforfuis produces acid from dextrose, levulose, galactose, and mal- 

 tose (Colas-Belcour and A. Lwoff, 1925), and also from dextrin and sol- 

 uble starch (D. F. Johnson, 1935b); G. fcaria (D. F. Johnson, 1935b) 

 ferments the same carbohydrates, with the apparent exception of levulose. 

 The reactions of C. campylum and C. striatum (Elliott, 1935a) are sim- 

 ilar to those of G. piriformis, except for fermentation of mannose and 

 failure to ferment galactose. Growth of C. campylum is accelerated by 

 several carbohydrates, in addition to those which are fermented. Ac- 

 cording to Glaser and Coria (1935a), dextrose and maltose are fer- 

 mented, and starch and cellulose are hydrolyzed, by Saprophilus oviformis 

 and Trichoda pura; starch and cellulose are attacked also by Chilodon 

 cucullus, Varamecium caudatum, and P. multimicronucleatum. Growth of 

 P. burs aria (Loefer, 1936c) is increased by dextrose, mannose, maltose, 

 dextrin, and melizitose, while little or no effect is produced by other 

 carbohydrates. No marked change in pH occurred in any case. 



Other carbon compounds known to accelerate growth of heterometa- 

 trophs include various alcohols and salts of certain organic acids. The 

 effects of several fatty acids on the growth of C. Paramecium have been 

 compared quantitatively by Loefer (1935a): the greatest acceleration 

 was produced by acetate, butyrate, and valerate. Recently, Provasoli 

 (1937a, 1937b, 1938a, 1938b, 1938c) has completed more extensive 

 investigations on nine colorless flagellates (C Paramecium, Hyalogo- 

 nium klebsii, Polytoma ohtusum, P. caudatum, P. uvella, P. ocellatum, 

 Polytomella caeca. Astasia quartana, A. chattoni). Acetate and butyrate 

 accelerated growth of all, while the effects of other fatty acids varied with 

 the species. Provasoli has pointed out that the negative results previously 

 obtained with certain salts probably resulted from their use in toxic 

 concentrations. The effects of sodium acetate on the growth of several 

 colorless species had been described previously by A. Lwoff (1929b, 



