H. GAFFRON 



adequate supplies of food and dwindling stores of energy will turn into 

 a surplus the moment photosynthesis has been duplicated in the test 

 tube. Popular articles and radio talks — spreading the lamentable 

 misconception that scientific research represents nothing but the first 

 step in technology — foster this notion by stressing the practical im- 

 portance of artificial food production from sunlight and carbon dioxide. 

 The error is easily demonstrable. The solar energy flux per acre and 

 year is a constant. Unless our devices are to be much more efficient 

 than the green plants and unless we are willing to spoil with ugly ma- 

 chinery an acreage equivalent to that now covered by beautiful forests 

 and pastures, artificial photosynthesis is not only Utopian but im- 

 practical. Even assuming we were to discover some sort of artificial 

 photochemical reduction of carbon dioxide into a digestible carbo- 

 hydrate with an over-all efficiency surpassing that of the plants which 

 use on the average two per cent of the incident radiation, it would not 

 help us much, since we need, not one product of plant metabolism, but 

 a thousand (16). Let us mention only the proteins among foodstuffs, 

 and wood and rubber among industrial raw materials. 



True, chemists have learned to make ammonia and nitrates 

 from atmospheric nitrogen. In that respect man is no longer dependent 

 on other natural sources. But up to now only the plant converts these 

 simple nitrogen compounds into proteins,* and so we are forced in a 

 second way, equally fundamental, to rely on the growth of plants for 

 our continued existence. In order to stretch our limited supply of 

 organic substances already formed, such as coal and petroleum, the 

 production of most compounds which plants can synthesize and which 

 we need in large quantities should be reserved for natural photosyn- 

 thesis, regardless of whether the chemist can duplicate the synthesis 

 in vitro. Oil, for instance, is too versatile a material to be converted 

 into rubber as long as plants are capable of continuously producing 

 essential raw materials like alcohol, or better still, rubber of excellent 



quality, t 



Denying that artificial photosynthesis will be the solution to a 

 serious and fascinating problem is not equivalent to saying that sun- 



* Nonphotosynthetic plants like yeasts are a good source of protein, pro- 

 vided they are fed with products of photosynthesis. 



t Guayule plants grown in California produce rubber far superior in 

 automobile tires to the synthetic compounds now available. 



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