50 Photosynthesis 



food of the animal kingdom is synthesized in the first 

 place from carbon dioxide and water through the 

 action of light on chlorophyll. The major part of 

 organic matter available on the land surface is the 

 product of the flowering plants. Buskin's 'vast fam- 

 ily of plants, which, under rain, make the earth green 

 for man, and under sunshine give him bread,' must 

 be extended from the grass to the plant in general, 

 and from man to the animal kingdom. Nor must a 

 secondary effect almost as important be overlooked — 

 the elimination from the atmosphere of the carbon 

 dioxide constantly poured into it, naturally by the 

 respiration of living things, and, one might say arti- 

 ficially, by combustion ; and its replacement by oxy- 

 gen. The warring processes, as is well known, keep 

 the amount of carbon dioxide in the atmosphere 

 roughly constant at about 3 parts in 10,000. It was 

 in searching for the process responsible for keeping 

 the air 'good' that the great chemist, Joseph Priest- 

 ley, made the first discovery of this activity of the 

 green plant in 1771." 



Now it is this fundamental process of photosynthe- 

 sis that Professor Baly and his collaborateurs have 

 been able to imitate artificially, apart from life alto- 

 gether. A clear account of their work up to 1922 is 

 given in Dr. E. J. Allen's Presidential Address to the 

 Zoology Section of the British Association meeting 

 at Hull, and some of the original papers by Professor 

 Baly and his fellow workers will be found in the 

 Journal of the Chemical Society, Volumes 119, 120, 

 121, 122. We have lingered over this matter because 



