194 THE CANADIAN NATURALIST. [Jime^. 



forms unhappily become prevalent among civilized nations, so as 

 to bring about the exhaustion of extensive tracts of the earth's 

 surface, at about the same period of time, — say, for instance^ in 

 the third or fourth generation hence ; in such case the demand 

 for cinereal manures, arising simultaneously over whole continents^ 

 would necessarily exceed all possible supplies, and incalculable 

 misery, in the form of famine and pestilence, must ensue. 



The exhaustion consex|uent on scanty manuring has been the 

 theme of many exhortations ; but the danger of similar evil from 

 injudicious or excessive manuring has not been sufficiently 

 insisted on. 



One more example of this danger is all for which space can be 

 afforded here. 



The growth of the wheat-plant may be divided, like that of the 

 biennial turnip, into three main periods ; — the first, during which 

 the growing power of the plant is chiefly employed in developing 

 its earliest leaves and its root ; the second, during which its vital 

 force is directed to increasing its foliage and shooting forth its 

 stalk ; the third, during which flowering and fruition take place^ 

 and the grain fills with nitrogenous and amylaceous compounds, — 

 the main objects of its culture. Now, injudicious manuring, with 

 excess of nitrogenous compounds and of the special ash-constituents 

 of straw, may cause such a development of stalk and leaf, and so 

 undue a consumption, by these, of food and force required to form 

 the grain, that, when this comes in its turn to the ripening period, 

 the conditions of its evolution fall short, and the result is a crop 

 of magnificent straw, with only half-filled ears. 



All these dangers and disasters disappear, all perplexity ceases, 

 and the course of the farmer becomes clear and safe, if he takes 

 for his guidance the natural laws of husbandry, — prominent among 

 which is that which enjoins the scrupulous restitution to the soil 

 of the ash-ingredients removed in the crop. 



Social and Political Aspects of the Question. — By 

 ignorance or neglect of these laws, ancient families, possessed of 

 vast estates, have been brought to ruin ; distress, the perturber of 

 dynasties, has befallen great nations ; and raighty empires have 

 fallen to decay. 



It is a remarkable fact^ and well worthy of the meditation of 

 statesmen, that the line which indicates, by its rise and fall, the 

 fluctuating price of corn in France, from year to year, during the 



