Vol. Ill, No. 4 



December, 1928 



The Quarterly Review 

 I of Biology 



THE CHLOROPLAST PIGMENTS, THEIR FUNCTIONS, 

 AND THE PROBABLE RELATION OF CHLORO- 

 PHYLL TO THE VIT AMINES 



By F. M. SCHERTZ 



Soil-Fertility Investigations, United States Department of Agriculture 



INTRODUCTION 



The present paper has been written to 

 show that by a long slow process we 

 liave come to know something about the 

 real nature of the chloroplast pigments. 

 Carotin and xanthophyll, being the 

 easiest to obtain, have been worked on 

 most, yet chlorophyll has always received 

 considerable attention. The latter has 

 been obtained only in solution until within 

 the past few years. All of the four chloro- 

 iplast pigments have been obtained in the 

 pure chemical state, and their probable 

 chemical formulae have been determined. 

 As yet little is known about the function 

 of any of these pigments in plant metab- 

 olism. The indirect evidence submitted 

 seems to show that chlorophyll in nature 

 is being broken down continually to form 

 numerous compounds. It should require 

 no great stretch of the imagination to see 

 that vitamines may be formed directly 

 from chlorophyll, with which they are so 

 intimately associated. 



THE CAROTINOIDS. EVOLUTION OF IDEAS 

 CONCERNING THE TWO CAROTINOIDS 



The evolution of the names of the pig- 

 ments shows us how misleading the names 

 given to the carotin pigments have often 

 been. Many names at times have been 

 proposed for what now is obviously the 

 same pigment. Botanists, chemists, and 

 plant physiologists each evidently chose 

 names suitable to them for the pigments 

 which were being investigated. A diver- 

 sity in nomenclature is found especially in 

 the yellow animal pigments and can be 

 traced in most instances to slight varia- 

 tions in certain of the simple properties 

 which were regarded as specific for the 

 various types of pigments. 



Often the variations were due to the fact 

 that the method employed for the isola- 

 tion of the pigment did not insure its 

 freedom from other pigments of similar but 

 not identical properties. Often the pig- 

 ment was examined in an amorphous con- 

 dition or in solution, without reference to 



459 



QUAE. EBV. BIOL., VOL. ill, NO. 4 



