75 



The cultui-e of librohlasls doslined for the cxpcrinienl 

 was dividod into two equal parts. One fragment was cul- 

 tivated in a mediiun composed of 1 drop of plasma anci 1 

 drop of a mixture of embryonic tissue juice and buffer 



D 



c 



> 

 (X 



5 6 7 8 



pH 



Fig. 6. 

 Ttie different hydrogen ion concentrations of the media in which the fifth 

 passage of the old strain of fibroblasts is cuhivated are indicated by the 

 abscissae. The ordinates indicate the relative increase of growth. Phosphate 

 buffer solutions were used. 



solution. The other fragment, the control, w^as cultivated 

 in 1 drop of plasma and 1 drop of embryonic tissue juice 

 to which previously had been added its own volume of 

 Ringers solution to compensate for the addition to the 

 experimental culture of buffer solution. Mica cover-slip were 

 used, because of the cover glass giving off alkali to the 



