9G Report of Experiments on the Growth of Wheat. 
to the growth of the plants be satisfied — if the soil be suitable, if 
it contains a sufficient quantity of alkalies, phosphates, and sul- 
phates, nothing will be wanting; the plants will derive their 
ammonia from the atmosphere, as they do carbonic acid. We 
know well that they are endowed with the faculty of assimilating 
these two .aliments ; and I really cannot see why we should search 
lor their presence in the manures we use." 
" The question of the necessity for ammonia in our 
manures resolves itself into the question of the necessity for 
animal manures, and upon the solution depends the entire future 
prospects of agriculture ; for as soon as we can dispense with 
bulky farmyard manure, by the use of artificial preparations, the 
productive power of our fields is placed in our own hands." 
Our former papers published in this Journal have shown that 
the results of direct experiment, as well as the general experi- 
ence of agriculture as practised in this country, are in the main 
confirmatory of the conclusions of Boussingault, and condemna- 
tory of those of Liebig, as above quoted; and the records of 
continued investigation given in this paper will afford further 
evidence in the same direction, in reference to some of the points 
in question. 
In his more recent works, however, Baron Liebig substantially 
affirms much of what we have from time to time maintained in 
correction of his own special doctrines. One example will 
suffice. In his most recent work — ' The Natural Laws of Hus- 
bandry ' — in the course of a good deal of illustration bearing 
upon the point, he says : — 
" It is easy to see that the accumulation of nitrogenous food by 
farmyard manure in the uppermost layers of the ground, so very 
important for the perfect growth of cereal plants, must chiefly 
depend upon the successful growth of fodder plants." 
Here, then, in direct contradiction to the views embodied in 
the sentences above quoted from his earlier writings, Baron 
Liebig now maintains the importance of the growth of fallow 
crops as a means of providing nitrogenous manures . for the 
growth of the cereal grains. He does so, however, not only 
without any acknowledgment of previous error on the point, 
but, as in other instances, seeks to cover his change of view 
by putting forth his present opinions as apparently only the 
necessary consequences of general or abstract principles laid 
down by himself, and by misrepresentation and ridicule of those 
whose corrections he adopts. 
Prior to the . appearance of Baron Liebig's work in 1840, 
numerous experiments, to a great extent suggested by a study of 
De Saussure's researches on vegetation, had been made, on a 
