126 



Scientific Proceedings (106). 



bean extract resulting from the Funk method seems to indicate 

 that it is the vitamine and not the impurities that is responsible 

 for the action. Many more experiments are of course necessary 

 to settle this point fully but these preliminary ones justify faith 

 that we are here dealing with a specific test for vitamine. We 

 hope to confirm them in much greater detail later. 



Diagram of Apparatus. 



I.) , U ' .3) 



r Rubber 

 BullS 



DDDDDDD 

 □□□□□□□ 



Counting Slide. 



. / \ / \ / \ Ti Rubber Cotton C D Counting Slide 

 A (2) (1) (3) B 



Bulb Plug 



The second question that arises is as to whether it is possible to 

 compare solutions by this test and actually measure vitamine 

 content quantitatively. Experiments in this direction have 

 consumed most of our time to date and have led to the technique 

 presented, since the earlier tests showed the necessity for rigorous 

 control in each feature of the test. We have not yet attained 

 satisfactory results in this respect but believe it is attainable by 

 improvement in technique. In this connection it must be borne in 

 mind that aside from uniform yeast suspensions, accurate cali- 

 bration and other mechanical details the test is biological. Yeast 

 cells like rats vary in metabolic activity, the vitamine necessary 

 to stimulate growth does not vary directly with concentration 

 but exhibits an optimum and minimum effect which must be 



