Yeast Growth in Pure Medium 313 



yeast to a marked degree. This experiment has shown that 

 the impurity in cane sugar can be practically eliminated after 

 one recry stall ization from alcohol and that the yeast growth pro- 

 moting property of cane sugar is not likely to be in the ash. 

 Our work has shown that cane sugar, purified either by fullers 

 earth, by recrystallization from alcohol or by combination of both 

 methods, is devoid of vitamine D. 



We have also made some experiments on the influence of the 

 medium on the subsequent growth of yeast. Yeast grown on a 

 medium poor in vitamine D, as medium O, and then used for 

 inoculation, gives a growth amounting to 0.4 mm. ; while that 

 grown on an agar-malt medium amounts to 2.25 mm. We can 

 conclude therefore that the yeast which we, at least, have been 

 using is unable to grow on a medium devoid of vitamine D. 

 When growth does take place, it is invariably due to two fac- 

 tors : firstly, the amount of vitamine D introduced with the seeded 

 cells, depending on the type of medium used; and secondly, the 

 vitamine-like impurity found in cane sugar. 



This impurity in cane sugar should be taken into account in 

 any subsequent work on this subject. The strain of bakers' yeast 

 that we have been using is unable to grow without vitamine D 

 and hence is unable to synthesize vitamine B in the absence of 

 vitamine D. 



153 (2113) 



Calcium in the blood. 



By WM. C. THRO and MARIE EHN. 



[From the Department of Clinical Pathology, Cornell University 

 Medical College, New York City.] 



In our continued investigation of the calcium in the blood we 

 have paid particular attention to furunculosis and to diabetes. 

 The results here published are part of over 225 determinations 

 made on human beings with the method described by Kramer 

 and Tisdall. 1 They state the normal is 9.2 — 11.1 mg. in 100 c.c. 

 of blood. 



i Kramer, Benj., and Tisdall, F. F., Jour, of Biol. Chem., 1921, xlvii, 475. 



