CRYSTALLIZATION AND STABILITY 



1785 



In contrast to the often reported instability of amorphous chlorophyll 

 preparations, crystalline powders of chlorophyll and bacteriochlorophyll 

 were found unchanged after six months storage at room temperature, at 





»* «? ^ .< * 



Pig. 37B.8. Microcrystals of the chlorophyllides (after Jacobs and Holt 1954). 



least as judged by the criterion of a high ratio between the absorption coef- 

 ficients in the two main peaks and in the trough between them. (These 

 spectroscopic "purity ratios," suggested by Zscheile, are particularly sen- 

 sitive to loss of magnesium.) 



