80 THE VITAMINES 



three cells were grown in two drops of water, with the addition of one 

 drop of a 1 per cent watery solution of polished or unpolished rice, 

 or malted milk. The division factor was taken as a measure of cell 

 activity and the first 24 hours were disregarded, to give the cells 

 the opportunity of adjusting themselves to the new conditions. The 

 following values were obtained: for white rice 0.34, for unpolished 

 rice 0.58, for malted milk 0.84. It was then possible, by the addition 

 of malted milk, to make the nutritive value of the white rice approxi- 

 mate that of the malted milk Other experiments were made with 

 various concentrations of malted milk and also with orange juice, 

 with the result that an addition of malted milk in higher concentra- 

 tions was of no further advantage, while orange juice showed a very 

 slight activity Addition of orange juice to white rice was followed 

 by better results than when added to unpolished rice, and with 

 orange juice alone, no paramecia cells could live after six days. In 

 these experiments, the influence of vitamines is easily recognized; 

 in fact, Flather was undoubtedly dealing in this case, not with one 

 vitamine but with the combined influence of the mixture of vitamines. 



Chambers (221) carried out similar experiments which demon- 

 strated the slight effect of potato extract; this displayed some influ- 

 ence only if the nutritive solution did not contain sufficient dietary 

 constituents; the same was true of malted milk. Peters (222) 

 cultivated Golpidium colpoda on a nutritive solution which con- 

 tained, besides salts, a mixture of some amino acids and in some 

 cases only one amino acid, tryptophane. The mixture of amino 

 acids was more active than the tryptophane alone. The first 

 divisions took place very slowly, though it was possible to keep the 

 cultures alive for three months through sub-culture. Peters ex- 

 plicitly emphasized that he could find no symbiotic microorganism. 

 He stated that in certain stages of development, a vitamine-like 

 substance seems to play a definite role. In all these experiments, 

 having for the purpose the study of the influence of the vitamines, 

 it is important that the food mixture used should be proved to be 

 vitamine-free. Abderhalden and Kohler (I.e. 127) investigated 

 the action of yeast extracts on flagellates (colpoda) with positive 

 findings. 



When we leave the protozoa, we find a dearth of available work 

 on other kinds of animals, although it should not be thought that 

 such work does not exist. This is specially true of the polycellular 



