332 



JAMES H. C. SMITH 



in the visible and ultraviolet regions of the spectrum. The absorption in 

 the ultraviolet is due very largely to the protein part of the holochrome. 

 In Fig. 6 is shown the effect of pH on the ultraviolet absorption of the 



0-2 04 0-6 



Volume 004N KOH 



Fig. 4. The alkaline titration curve of protochlorophyll holochrome. 



holochrome. At about pH 9-7, spectral changes become obvious. Perhaps 

 it is noteworthy that at this alkalinity the inhibition of the protochlorophyll 

 conversion begins to intensify significantly. 



1-8 _ 



300 



600 



700 



400 500 



Wavelength (m//) 



Fig. 5. The absorbance of protochlorophyll holochrome in the visible and 

 ultraviolet regions of the spectrum. 



