THE VITAMINES IN THE ANIMAL KINGDOM 79 



mine. It may then be possible to experiment with the pure cul- 

 tures of the intestinal bacteria indigenous to the particular species, 

 to produce a normal dietetic condition without the addition of vita- 

 mine. Only then shall we be in a position to state that vitamines 

 are necessary for the existence of the entire animal kingdom and 

 eventually for the whole organized world. 2 Sometimes, however, 

 a poor idea has some truth in it, and this seems to be the case with 

 Portier 's hypothesis. It is possible, as we have already said, that 

 certain animals and plants obtain their vitamines through a sym- 

 biosis with bacteria. This idea was tested experimentally by 

 Portier and Randoin (217). They made the observation that 

 rabbits fed on sterilized cabbage and carrots developed an avitamin- 

 osis, while rabbits which received an addition of the excrement of 

 another rabbit on the same diet remained normal; still, it is not 

 quite clear to us why rabbits kept on the same diet should possess 

 a different intestinal flora than those receiving an addition of feces. 

 It appears that these experiments, serving to demonstrate the 

 importance of the symbiotic intestinal bacteria, could be much better 

 explained on the basis of the vitamine content of the feces. 



PROTOZOA 



Investigations on protozoa were carried out chiefly with paramecia. 

 Lund (218) has recently shown that he grew these single-cell organ- 

 isms on yeast extract, but the details of the experiment have not yet 

 been published. Calkins and Eddy (219) worked with Paramecium 

 aurelia kept on two different nutritive media hay infusion and 

 cooked flour. As a source of vitamine, a preparation of vitamine B 

 of the pancreas was used. The number of daughter cells varied 

 within the limits of experimental error, and therefore it was con- 

 cluded that the vitamine exerted no influence on this type of animal. 

 Flather (220) obtained somewhat dissimilar results from experiments 

 in which pure cultures of species of paramecia were maintained 

 always under the same experimental conditions; in every experiment, 



2 Portier (212) has recently formulated a hypothesis in which he assumes 

 that in certain plant and animal organs, there are heat resisting bacteria 

 (called symbiotes) which behave biochemically like vitamines (Bierry and 

 Portier (213). Just now, we shall not discuss this theory itself for it appears 

 to be lacking a real basis, and besides it has already been made the subject 

 of an earnest critique by Delage (214), Lumiere (215) and Ranc 



