Paramecium calkinsi sp. n. 



137 



of more or less carbohydrate in the food mixtures consumed by 

 man and the higher animals, and the fact that sugar is a constant 

 constituent of the blood. Furthermore, it has been concluded 

 that carbohydrates are essential for the proper metabolism of the 

 fats because ketone substances may be excreted in diabetes when 

 sugar fails to be burned up in the normal manner in the organism. 



We have found that rats receiving a diet in which the amount of 

 digestible carbohydrate was at most exceedingly small can grow 

 from an early age to adult size. The rations which we fed included 

 protein — casein, edestin, or lean beef which had been thoroughly 

 extracted with boiling water — inorganic salts, agar-agar, lard, 

 butter fat and 04 gm. daily of dried brewery yeast furnishing 

 vitamin B. The yeast can scarcely be regarded as a significant 

 source of available carbohydrate. Success was likewise attained 

 in experiments in which no agar-agar was introduced. In the 

 latter case the only obvious sources of preformed carbohydrate 

 were the yeast employed and such carbohydrate impurities as 

 might still adhere to the protein preparation fed. 



64 (1646) 

 Paramecium calkinsi sp. n. 



By LORANDE LOSS WOODRUFF. 



[From the Osborn Zoological Laboratory, Yale University.] 



There are at present four well-established species of Paramecium 

 (P. aurelia., P. caudatum, P. bursaria, and P. putrinum) which 

 fall naturally into two quite clearly defined groups. One group 

 comprises Paramecium aurelia and Paramecium caudatum which 

 are characterized by a relatively long spindle-shaped body. The 

 other group includes Paramecium bursaria and Paramecium 

 putrinum which exhibit a somewhat shorter and broader form, 

 with a tendency toward a dorso-ventral flattening. All the species 

 have a single micronucleus except Paramecium aurelia, which has 

 two micronuclei each showing characteristic 'endosome' structure. 1 



1 H. S. Jennings and G. T. Hargitt: "Characteristics of the Diverse Races of 

 Paramecium." Journal of Morphology, 1910, xxi, 495. L. L. Woodruff : "Paramecium 

 aurelia and Paramecium caudatum," Journal of Morphology, 1911, xxii, 223. 



