CIILOROPII YLL 21 



conversion of kinetic to potential energy. They also found that 

 iron is present in the colourless part of the ehl()ro|)lasts of the green 

 plant. Snn and iron are necessary for the de\elopnient of the 

 chlorophyll although the pigment itself contains no iron. It, 

 hoAvever, according to Willstater, contains magnesium as an integral 

 part of the molecule. Fenton, in 1907, showed that carbon-dioxide 

 and water could combine to form formaldehyde when reduced by 

 metallic magnesium. From Moore's work, it may be inferred : 



(1) That inorganic colloidal systems evolved in point of time 

 before organic colloids. 



(2) That under the influence of sunlight and in the presence of an 

 inorganic catalyst, the chlorophyll system developed. 



(3) The inorganic system is able to utilise light only of short 

 wave-length, while 



(4) The chlorophyll system acts as a transformer (p. 164) and 

 utilises the more abundant longer waves (Fig. 1). 



To sum up, man obtains the energy necessary for his main- 

 tenance and for the performance of physical work from the 

 disruption of proteins, carbohydrates and fats, synthesised in 

 the first instance by green plants which trap and store solar 

 energy. Historically, and until quite recently, the energy of sun- 

 light, apart from an insignificant amount drawn from the tides, 

 was the sole income of energy available for the world. Mankind 

 still maintains himself solely on the energy derived from the 

 sun through the intermediary of plant and animal metabolism, 

 but he derives his energy for work to an increasing extent from 

 a legacy of potential energy laid by in former times. He has 

 devised detachable limbs (machines and tools) able to utilise the 

 energy of coal, petrol, etc., of which he could not avail himself 

 without their aid. This has made possible an enormous increase 

 in the world's work — work done no longer by human beings and 

 beasts of burden, but by inanimate machines using the energy of 

 fire, electricity, etc. To-day, a single machine does the work of 

 an army of men. In this way man conserves present-day solar 

 energy and lives on the banked income of past ages. Some time 

 in the future he may learn how to synthesise food from inorganic 

 constituents by the use of any form of energy available. Then 

 and only then will he be able to dispense with plant life. The 

 energy available for each man is his income. Stored energy is a 

 legacy deposited in Nature's " bank." 



Further Reading 

 Moore. " Biochemistry." Edward Arnold. 



