60 PHOTOSYNTHESIS 



ence with the areas of land required for food production would lead to 

 severe economic disturbances. 



Moreover, the fact is too readily forgotten that agriculture is a very 

 sensitive and highly complex industry. Agriculture deals primarily with 

 biological processes involving all the fine adjustments and balances of a 

 growing organism. In the growth of a plant sunlight is but one of a 

 number of determining factors. The fact that during critical periods in 

 the development of a plant slight changes in climatic conditions during 

 a short time may greatly reduce or entirely destroy a crop, serves to empha- 

 size the hazard of obtaining energy through the intermediary of plants. 

 In agriculture water supply and temperature are far more variable and 

 determining factors than light intensity. On the proper coordination 

 of these two factors, probably more than any other, depends the success 

 of crop production. The multiplicity of pests and diseases which annually 

 destroy a large per cent of our crops greatly increase the hazards of this 

 industry. It is evident, therefore, that the plant at best is not only very 

 inefficient in storing solar energy but is also rather unreliable. The 

 plant not only produces organic compounds of great complexity from 

 carbon dioxide and water by the use of solar energy, but also uses a con- 

 siderable portion of this material for its own life activities. Most plants 

 are, however, thrifty beings. Of the products of their labor they lay by a 

 small portion. From these savings the succeeding generation gains its 

 strength for growth until it is a self-supporting organism. Man lives 

 largely by taking this surplus from the plant for the maintenance of his 

 own life. Agriculture has been largely concerned with the study of con- 

 ditions of soil, climate and cultivation for the production of this surplus of 

 the plant. It has given little consideration to the vital question, the process 

 by which the plant manufactures its products, i.e., photosynthesis. As has 

 been stated, a clearer understanding of this process is of importance not 

 only that we may understand the internal working of the plant, but now 

 also as a guide to accomplish outside of the living organism what the 

 plant is doing. *■■ i'W'jflJi'^f 



In conclusion, then, we may say that solar radiation is the greatest 

 and an inexhaustible supply of energy for our earth. The chlorophyllous 

 plant is a converter of this energy into potential energy ; it is from a 

 chemical viewpoint a great reducing mechanism, producing compounds 

 which can combine with oxygen. The transformatioi. of matter involved 

 m this conversion of energy, that is, the chemistry of photosynthesis and 

 metabolism present an exceedingly complex picture. The main reason for 

 this ai>parent complexity is that photosynthesis is intimately connected 

 with the vital process of the plant and hence subject to the manv fine 

 adjustments characteristic of living protoplasm. No analysis of the 

 process of photosynthesis in ])lants is reliable which does not give due 

 regard to this fact. This need not mean, however, that a photosynthesis 

 attaming the same or analogous results as the plant can never be achieved 



