the pigments which they contain were called chloroplast pigments. 



From these observations, chloroplast pigm.ents are the primary- 

 absorbers of light by plants. The chloroplasts are the transformers 

 of absorbed radiant energy into chemical energy. The raw materials are 

 the carbon dioxide of the atmosphere and the water of the planto The 

 final products are organic matter, that is supplied to the plant cells, 

 end gaseous oxygen. As green plants provide the organic food for vir- 

 tually all the other living things, chloroplast pigments are an indis- 

 pensable link in the chain of unique organizational forces that characterize 

 living organisms o From a chemical standpoint, the over-all process of 

 photosynthesis could, therefore, be written 



Sunlight + (Pigments) + xCOg + XH2O > 



(Pigments) + (CH2"=0)^ + XO20 



Properties of the Chloroplast Pigments 



Because of their basic role in Nature, chloroplast pigments have 

 been the subject of many intensive investigations. For the interpreta- ) 

 tion of their photosynthetic reactions, the pigments were extracted from 

 plants, and many attempts were made to isolate them in a state of high '"' 



7 ft Q 



purity's sV„ This line of investigation led not only to the discovery 

 of a number of chloroplast pigments but also to the development of 

 several selective separatory methods that were destined to serve for the 

 separation and purification of all kinds of chemical substanceso These 

 analytical techniques have now become indispensable tools for most in- 

 vestigations concerned with cher.ical compounds and their reaotions^o 



Chloroplast pigments proved to be remarkably sensitive and labile 

 substances. They were destroyed by many chemical reagents and by many 



