204 THE CANADIAN NATURALIST. [June, 



This accuraulative and distributive agency of a normal rotation 

 of crops, oTOwing (by hypothesis) on atypical soil, most strikingly 

 reflects, in what may be termed the physiological mechanism of 

 agriculture, the regulative influence exercised in mechanics by the 

 fl -wheel ; which, in like manner, during each rotation, stores up 

 the momentum gained at the period of maximum impulsion, to 

 give it out as work at the period of maximum resistance. Thus 

 much being admitted by all with reference to the supposed typical 

 soil, there will only remain for consideration the case of soils fall- 

 ing so far short of this hypothetical perfection, with respect to 

 their natural ammoniferous endowments, that the total supply, 

 including that collected by the leguminosae, proves inadequate to 

 meet the demand of the cereals. The utility, in such cases, of 

 nitrogenous manures, and the propriety of the husbandman's 

 intervention, thus artificially to make good the defect of the 

 natural ammonia-supply, will not by any one be contested. 



Thus, point by point, the main ground of difference (the alleged 

 preponderating value of nitrogen) seems reducible to a mere 

 statistical question ; — how many European corn-fields are relatively 

 poor in this or that cinereal ? how many are deficient of humus, 

 or water, or air ? how many fall short as to their natural ammo- 

 nifer- us properties ? Whichever element, fixed or volatile, might 

 be indicated by the result of this inquiry, as deficient in the largest 

 number of cases, might be described as the element o^ preponder- 

 ating " importance, without violence to the opinions of either 

 party. 



This method of settling the great nitrogen-controversy would, 

 however, still leave open for discussion a grave question concerning 

 this element of plant-food, — a question which the intellectual for- 

 ces, heretofore expended in conflict, might be usefully combined to 

 set at rest. This question is, how much ammonia is it possible, in 

 the present state of our industrial resources, to provide for soils 

 not naturally well supplied therewith ? If high farming is to 

 become universal, and to be carried out on second and third class 

 Boils, at as high a pitch above their natural ammoniferous endow- 

 ments, as is now aimed at in many English farms, the demand for 

 ammonia seems likely to exceed all the means at our disposal for 

 its supply. 



The saving of urban ejecta, and the consequent return to the 

 soil of the enormous masses of cinereals now wasted, appears 



