632 ANNUAL REPORT OF THE Off. Doc. 



He gave his plant nothing but distilled water. In five years the 

 plant had gained 164 lbs. weight, and the earth had only lost two 

 ounces. He declared, therefore, that all the plant required was 

 water. He did not know that the atmosphere furnishes a very im 

 jtortant food in its carbonic acid gas with which the plant manu 

 factures starch and sugar-like substances. 



Besides starch and sugar the plant manufactures many compounds 

 containing nitrogen. We all know that the air is in reality a sea of 

 gas, mostly nitrogen. Early in the last century it was proved that 

 plants could not make use of this element directly from the atmos- 

 phere, but that it had first to be elaborated into some digestible 

 compound. For many years it was generally accepted as a fact that 

 plants derive all their nitrogen from the soil and that in no way 

 can the nitrogen of the air be utilized. About fifteen years ago it 

 was shown that some members of the vetch family are exceptions 

 to this rule. In the light of pure science this was at the time re- 

 garded as a discovery of remarkable interest. Later on it was 

 found that this knowledge might be turned to practical account. A 

 few years ago Dr. Wiley, Chief of the Department of Agriculture 

 of the U, S, government, gave a detailed account of the manner in 

 which this peculiar faculty of members of the vetch family is util- 

 ized. It seems that great practical results have already been 

 achieved. 



The most important work which has been done in the field for 

 pure science for the practical worker, is in connection with the study 

 of soil constituents. This was initiated in 1840 by a German chemist, 

 Liebig, who is often called the ''Father of Agricultural Chemistry." 

 The clue to this work seems self-evident to-day, but was much ridi 

 culed by many of this great man's contemporaries, scientists as well 

 as farmers. Liebig argued that whatever is found in the ashes of 

 a plant after burning must have been originally obtained from the 

 soil; and further, that, whatever is found was probably introduced 

 for some purpose. The antagonism which this common-sense state- 

 ment created is surprising; there were factions for and against 

 Liebig. Indeed there was considerable calling of names, to which 

 many pamphlets, appearing at that time, attest. All this petty 

 w^arfare is now forgotten, but the work of this great genius was 

 built upon broad and solid foundations. As a result we may say 

 that all plants require K, Ca, Mg, P, S, and Fe, and upon this the 

 further knowledge which has since been accumulating rests the 

 great science of agricultural chemistry. 



The practical application of scientific truths is rarely evident at 

 the time of the discovery, and it is for this reason that scientists do 

 not always receive due recognition for their labors. In fact, the 

 name of the pioneer is sometimes forgotten by the time his work is 

 bearing fruit. Many new facts have been discovered in this field, 

 some of them being at present simply of scientific interest. I might 

 mention that it has been found that some of the elements which are 

 considered essential may be replaced by similar elements. It has 

 been found that the element of potassium may be replaced by the 

 rare elements Caesium and Kubidium. Who can tell whether a dis- 

 covery of this kind will ever assume a practical aspect? 



Enough has been said to indicate that pure science and horticul- 



