206 THE CANADIAN NATURALIST. [June, 



be found to exceed the ammonia-accumulating power of the legu- 

 minosas, when grown, in due proportion, in rotation with cereals; 

 under such hypothetical conditions the drain of ammonia will 

 doubtless, in a still larger number of cases, exceed the natural 

 supply, and compel recourse to ammoniacal manures. 



Liebig's view of the sufficiency of natural ammonia-supplies, 

 even for the purposes of high farming, when fairly and skilfully 

 conducted on suitable soils, is not incompatible with the opinion 

 that artificial ammonia- supplies may become in an increasing 

 degree the husbandman's principal requirement hereafter, under 

 the modified agricultural conditions rapidly sketched above. 



How far it may be wise to encourage the development of such 

 a system, is a serious question. For, unl-ss some cheap source of 

 ammonia should be in the meantime discovered, the exhaustion 

 of the guano-deposits (relatively a limited quantity) must, under 

 such circumstances, bring ruinous disaster in its train. The col- 

 lapse of the foundation would of necessity involve that of the 

 edifice reared thereon ; and large populations, called into existence 

 by these factitious means, would find themselves deprived, more or 

 less suddenly, of their accustomed food-supplies. 



Considered from this point of view, the great " nitrogen ques- 

 tion " merits the gravest consideration, not only of agriculturists, 

 but also of statists and politicians. 



Thus far the matters in dispute seem capable of settlement in 

 terms admissible by both the contending parties ; but the questions 

 at issue comprise points, or rather perhaps are presented in forms, 

 on which the divergences of opinion appear too wide to afford any 

 prospect of harmonization. 



Thus, for example, it is affirmed on one side, and denied, point 

 blank, on the other, that potash acts " specifically " (i. e., otherwise 

 than in conformity with Liebig's law) in promoting the growth of 

 the leguminous plants, such as beans and peas. Those who main- 

 tain this view allege, as their reason, that the legurainosae, though 

 . characteristically rich in nitrogen, require potassic, not ammoniacal 

 manures. The fallacy of this reasoning becomes apparent when 

 it is considered, first, that the leguminous plants, absorbing as they 

 do ammonia in abundance by their leaves, can naturally dispense 

 with a supply of this aliment to their roots ; secondly, that of all 

 the ingredients in the ash of the leguminosae, lime and potash are 

 the two most prominent j so that for soils abounding in lime (as 



