THE CHLOROPLAST PIGMENTS 



should have given rise to an eager search 

 for additional dietary components essen- 

 tial to life. 



It has been shown by many investigators 

 that certain amino acids such as tyrosine, 

 cysteine, tryptophane, histidine, arginine 

 and lysine are more or less indispensable 

 to the animal organism. 



Hopkins made the prophetic statement 

 that no animal can live upon a mixture of 

 pure protein, fat and carbohydrate even 

 when the necessary inorganic material 

 is supplied. The animal body is adjusted 

 to live upon the tissue of plants or animals 

 and these contain countless substances 

 other than protein, fat and carbohydrate. 



The firmly established importance of the 

 vitamines for the existence of certain 

 animals and plants, organisms far removed 

 from each other genetically, makes it 

 apparent that these substances are of 

 universal importance to life. 



CONCLUSION 



Thus far in this paper it has been only 

 my intention to summarize what is 

 already known regarding the subjects 

 which have been discussed. In that 

 which is to follow nothing new will be 

 presented, but what has already been 

 cited will be placed in a new order with 

 the hope that some new relations may be 

 discovered. This article is written with 

 the hope of stimulating interest in the 

 chloroplast pigments and not with the 

 intention of proving the truth or falsity of 

 any of the ideas herein presented. It is my 

 desire to have the reader of this paper sit 

 down and honestly ask himself if there is 

 a possible relation such as will be sug- 

 gested here. It is up to each one of us to 

 decide for himself whether there is any 

 reJ ation or none . Conscientious thinking 

 on the part of the reader is all that I ask. 

 What I write is the result of ten years work 

 and study of the chlorophyll question and 



is offered only as a report of progress made 

 in the solution of the problem. Absolute 

 proof of the real nature of chlorophyll will 

 most likely be many years in the future. 

 But at least for the present no harm should 

 be done in pointing out a possible relation 

 to other substances which have long been 

 studied but whose real nature has never 

 been determined. 



In thinking over this problem we should 

 keep ever in mind that Wills tatter worked 

 for many years with the green pigment of 

 leaves before he finally isolated it. He 

 had many workers, an abundance of funds 

 and laboratory facilities which most of us 

 never dream of, and even then only after 

 many discouragements did he finally sepa- 

 rate the pure substance, chlorophyll. A 

 simple discovery regarding the chemical 

 nature of chlorophyll made possible the 

 solution of this problem. In addition to 

 the material equipment which he had, he 

 possessed something far more worth while 

 than all of these, for within himself there 

 was a determination and the desire to 

 know the truth for the truth's sake and 

 for no other reason. I have been told that 

 when he found that chlorophyll contained 

 magnesium instead of phosphorus, he 

 was cautioned by some of his colleagues 

 that he should go slow in publishing 

 his findings. Instead, he soon boldly 

 announced his results to the scientific 

 world and for more than fourteen years his 

 work has stood unchallenged. In fact, 

 the story of his work on chlorophyll is as 

 fascinating a story as may be found in the 

 scientific world. There seemed to be one 

 test which he applied to all of his work, 

 and that test was that the result should 

 satisfy himself; for he realized that if he 

 was not honest with himself he could not 

 expect the scientific world to accept the 

 results of his investigations. 



In regard to the history of the prepara- 

 tion of pure chlorophyll a point will 



