92 LUTHER BURBANK 



tory is the original transformation of inorganic 

 materials into an organic compound. 



Of course there are other important stages of 

 the work through which final assimilation is 

 accomplished. To make starch or sugar into 

 protoplasm it is necessary to bring another ele- 

 ment into the combination. This element is 

 nitrogen. There must also be incorporated small 

 quantities of a number of minerals ; notably com- 

 pounds of phosphorus and potash and lime, but 

 including six or eight others that must be present 

 in infinitesimal amounts. 



And the building of these substances into 

 combination with the sugar in such a way as to 

 produce the substance called protoplasm, the 

 basis of all life, constitutes the culminating stage 

 of the miracle. But the way in which this is 

 effected is even less clearly understood. 



We do know, however, that all these sub- 

 stances are brought to the plant in watery 

 solution. 



Nitrogen constitutes about four-fifths of the 

 atmosphere, as everyone knows, and hence it 

 seems rather strange that the plant does not 

 draw what nitrogen it needs from this source, 

 in particular since it gets its carbon from the air. 



But the plant, no less than the animal, might 

 starve to death from lack of nitrogen even while 



