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Scientific Proceedings (108). 



sion + Naegeli, (2) vitamine sol. + Naegeli, and (3) vitamine 

 sol. + yeast suspension + Naegeli. The tubes are incubated for 

 20 hours at 30 0 and the fermentation then interrupted by heating 

 to 70 0 for a few minutes. The contents of the test tubes are then 

 transferred to special centrifuge tubes, the bottom part of which 

 ends in a capillary 2J/2 cm. in length and divided in mm. The 

 tubes are centrifuged at 2600 r.p.m. for 15 min. and the reading 

 made without much delay as there is a tendency for the yeast 

 cells to swell up slightly after a time. Sterility during the entire 

 process, excepting centrifugation, is of paramount importance. 

 The results obtained with this method were as follows : The pro- 

 cedure was so well standardized that the controls with yeast 

 suspension alone were practically constant. Duplicate experi- 

 ments checked very well so that the method was applicable for 

 a quantitative determination. In developing the test, autolyzed 

 yeast was used as a source of vitamine. It was noticed, however* 

 that the amount of cells obtained, as shown by the reading on the 

 centrifuge tube, does not increase double if the vitamine amount is 

 doubled. By trying varying amounts of vitamine a curve was 

 established, using autolyzed yeast as standard, which permits of 

 comparison between an unknown vitamine content and our stan- 

 dard. The sensitivity of the method is .0001 c.c. of autolyzed 

 yeast, and the amount to be tested is best made so that it corre- 

 sponds to our curve between 0.01 and 0.1 c.c. of autolyzed yeast. 

 In this interval the curve climbs up abruptly and small differences 

 can be read with facility. It was found also that contrary to the 

 method of Eddy, where the number of cells incubated varies the 

 controls to an undesirable extent, this is not the case in our method. 

 The variation of cells in our yeast suspension has very little effect 

 on the final result. 



First of all, we were interested to know in how specific this test 

 is for B-vitamine. Among the substances found negative in their 

 action were allantoin, hydantoin, nicotinic acid, several purine 

 and pyrimidine bases and several aminoacids. Pilocarpine found 

 by Dutcher to be curative in pigeon beriberi was found inactive, 

 while thyroid gland was active, as it contained the celullar con- 

 stituents. An extract of pituitary gland was also found active 

 for the same reason. In a second series the substances isolated 



