THE NEW FERTILIZATION. 101 



and the water under tribute at the same time, each class and 

 individual selecting that which is necessary to the performance 

 of its function. 



The human body, in common with all other animal bodies, 

 is made up of certain elements existing in unlimited quantities 

 in the atmosphere and in the mineral world, but before these 

 substances are available as human food they must pass through 

 a transformation they must be taken, utilized and trans- 

 formed by the vegetable kingdom. Vegetables and suitable 

 vegetation we may use as food, but not inorganic matter. 



The plant which forms the growing crop must have its food 

 prepared by a precisely similar process of indirection. We 

 were accustomed to think that the rootlets of a plant, coming 

 in contact with the inorganic elements of the soil, had the 

 power to assimilate them directly, thence to build them into 

 tissue for the use of man and beast. Within limits we still 

 believe this to be true, but it is now known that, with the ex- 

 ceptions noted, plants and animals hav te in common, that 

 neither can live directly upon the inor^nnic. The elements 

 which serve as the crude food materials of plants must un- 

 dergo a decomposition and transformation by the operations of 

 some lower order of life before they can become available as 

 nourishment, just as the inorganic must be broken down and 

 rebuilt into plant life before it becomes available for the sus- 

 tenance of man. Take the substance silica for example, which 

 is most familiar to us in the form of common sand. It is 

 an important constituent of plant food, yet it is highly insolu- 

 ble and would seem to be the least suitable of inorganic sub- 

 stances to enter into a plant's circulation least likely to be- 

 come available as a plant tissue-building material. 



We may imagine a minute fragment of silica or any other 



