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suitability for particular crops, and its response to manuring in 

 various directions. Thus an unknown soil may by analysis be 

 allotted to its known type, deviations from the type can be 

 recognized and conclusions may be drawn as to the connexion of 

 these defects. One of the services, then, which the farmers in 

 every country may very properly expect from the scientific man, is 

 such a survey of the principal soil types, affording the necessary 

 datum lines by which the comparative richness and poverty 

 of any particular soil may be gauged. In an old settled country 

 like the United Kingdom such a survey would guide the farmer in 

 his selection of manures ; in a new country the advantages would 

 be even more apparent, as the areas appropriate to particular crops 

 would be indicated, and settlers would be saved from many 

 expensive attempts to introduce things for which their land was 

 unsuited. It would also be possible to indicate the measures which 

 should be taken to ameliorate the nature of the poorer soils. The 

 main facts of the nutrition of the plant have been so long 

 established that it is not always realized how much still remains 

 unknown. It has become a commonplace of the text-books that 

 the plant needs nitrogen, phosphoric acid, potash, often in excess 

 of the quantities present in a normal soil ; so that these substances 

 alone are considered of manurial value, other necessary materials 

 like lime, magnesia, iron, sulphuric acid, and chlorine being 

 practically never lacking under natural conditions. But the function 

 of these substances in the development of particular plants, the 

 manner in which the character of the crop is affected by an excess 

 or a deficit, is still imperfectly apprehended. Examine the effects 

 of silica, for example. A plant that is being starved of phosphoric 

 acid can economize and make more use of its restricted portion if 

 a quantity of soluble silica be available. There is no possibility 

 of replacing phosphoric acid by silica in the general nutrition of 

 the plant but the abundance of silica at the disposal of the cecals 

 certainly enables them to diminish their call for phosphoric acid 

 from the soil. Much in the same direction lie the researches which 

 are being pursued with so much vigour by Loew and his pupils in 

 Japan on the stimulus to assimilation and plant development which 

 is brought about by infinitesimal traces of many metallic salts not 

 usually recognized as being present in plants at all. It has been 

 often recognized that substances which are toxic to the cell in 

 ordinary dilutions, may, when the dilution is pushed to an extreme 

 reach a point at which their action is reversed and begins to 

 stimulate. Probably some of the materials used as fungicides and 

 inhibitors of disease act in this fashion by strengthening the whole 

 constitution of the plant rather than by directly destroying or 

 checking the growth of the fungus mycelium. The subject is 

 certainly one which promises to yield results of value in practice, 

 and calls for more extended and exact observation. The im- 

 portance of research on the particular function of the various con- 

 stituents of the crop lies in the fact that it is only b)'' the possession 

 of such knowledge wc may possibly influence in desired directions 

 the (luality of our crops. The "strength" of wheat, however, is 



