Measurement of Vitamine Content. 127 



established in the comparative standard used. These factors 

 complicate the problem. The following results show some of 

 these difficulties and are given rather to suggest the problems 

 than as conclusions. All these features are under study and we 

 hope soon to present a report of progress toward their solution: 



table 11. 



Vitamine Preparation Used. 



Concentration. 



Period of Incu- 



Count of Incubated Tubes. 



bation. 









Vitamine Tube. 



Control Tube. 



Water sol. vitamine from 













c/i 



24 hours 



5312 



5 



F24 



c/2 



24 



3192 



28 



F24 



c/i 



18 



6l6l 



14 





C/2 



18 



472 



58 





c/8 



18 



59 



20 



F24 



c/i 



18 



9724 



123 





C/2 



18 



362 



60 





c/8 



18 



85 



9 



F24 



c/i 



18 



6248 



48 





C/2 



18 



729 



60 



F24 



c/i 



18 



8531 



97 





c/i 



6 



24 



2 





C/2 



6 



147 



6 





c/4 



6 



119 



3 



The above were made with the first pipettes before accurate calibration or stan- 

 dardized suspensions were made. The following were results with calibrated pipettes 

 but the suspensions were not entirely uniform as shown by a count of 25 units of the 

 suspension used. These units were taken after an hour shaking and varied as follows : 

 1 8-3 7-1 2-1-3-2-2-0-1 5-3 5-46-7 8-5 7-6-2 7-3 1-33-1 2-1 1-1 7-34-2 1-60-29 cells. 



F24 



c/i 



6 



27 



15 





C/2 



6 



9 



one control 





c/4 



6 



14 



for series 





c/i 



6 



20 



6 





C/2 



6 



16 



one control 





c/4 



6 



60 



for series 





c/8 



6 



12 





The following were made with calibrated pipettes and a suspension for which 

 eight counted units resulted as follows (2 hours shaking) : 4-2-3-1-3-5-2-3 cells. 





c/i 



22 hours 



492 



1 





C/2 



22 



660 



one control 





c/4 



22 



102 



for series 





c/8 + 



22 



11 





