PHOTOSYNTHESIS 



light will not be used at all in the technology of the future. In selected 

 places, such as roof tops in sunny countries, bare rock, and deserts inac- 

 cessible to irrigation, sunlight may soon be utilized to produce heat or 

 electric power or even to drive some photochemical process like that 

 of hydrolysis. These possibilities have exactly as much and as little re- 

 lation to the problem under discussion as exists between any other 

 common source of energy and a filled granary. There is every indica- 

 tion that products of plant photosynthesis will be needed ever more 

 urgently, not only as food but also as fuel and building material. Re- 

 cent technological mventions indicate that wood, strengthened with 

 wood-derived chemicals, will be in even greater demand than now. 



One and one-half billion of the two billion humans on earth are 

 illnourished or permanently hungry, "There has never been enough 

 food for the health of all people" (18). Since this globe offers only a 

 certain area of habitable and tillable ground, it is obvious that 

 populations will have to be adjusted to a certain optimum density 

 determined by the general standard of living that man is capable of 

 attaining or willing to endure. 



We have ample testimony of the improvident way in which 

 the ancients exhausted their supply of wood. The mountains of 

 Persia, Syria, Greece, Dalmatia, Italy, and Tripolitania are now to a 

 large extent barren and infertile. The goats of the Arabs are said to 

 have done away with the last traces of vegetation in North Africa, 

 thus allowing the desert sands to advance to the shores of the Medi- 

 terranean. The changes in climate brought about by the denuding 

 and erosion of the sites of the most important early civilizations make 

 it difficult or impossible to retrieve the lost fertility of the land. 



Are we wiser today? The rate of consumption of coal and pe- 

 troleum in the world today (1.75 X 10^ tons carbon per year) is 

 roughly one-tenth of the rate of the total carbon assimilation achieved 

 by the land plants on earth (1.6 X lO^" tons carbon per year) (14). 

 The coming industrialization of Asia will soon diminish the gap be- 

 tween the demand for, and the supply of, organic material. The 

 established reserves of oil in the United States, according to official 

 figures, are about twenty billion barrels. They are being used up at 

 a rate of one and one-half billion barrels per year. The industry 

 insists upon a more optimistic outlook, based on the (ever-declining) 

 rate of new discoveries. True or not, considering also the certainly 



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