as a Manure for Ttimips. 
51 
however we may grant the facts, we may still doubt the inductive 
reasoning on which this theory of Sprengel's is founded ; and, 
consequently, on more occasions than one I have endeavoured to 
show that the conclusion thus come to cannot legitimately be drawn 
from such premises.* To the details of the objections which have 
been taken to the theory in question, it is not necessary now to 
revert. With the same data in view Professor Johnston has come 
to a very different conclusion. His theory is that " the whole 
effect of bones cannot in any case be ascribed exclusively either to 
one or the other of their principal constituents ; and that the 
organic part performs the most prominently and most immediately 
useful oflfice ; but that the earthy part nevertheless affords a ready 
supply of certain inorganic kinds of food which in many soils the 
plants would not otherwise easily obtain." This conclusion the 
Professor places in opposition to Sprengel's, on the ground that 
the organic part of bone is analogous to horn, hair, wool, &c., 
valuable fertilizers; that if applied alone, it is known to be a 
potent fertilizer ; that, in fact, the liquid in which bones are 
boiled in Cheshire and Lancashire, even after the fat has been 
skimmed off, and when the size (or dissolved gelatine) has become 
so weak that it will not answer for stiffening, is readily bought up 
as a manure ; and that large bones put about the roots of vines 
and trees will promote their growth, and yet after the lapse of 
years these same bones may be dug up nearly unaltered in form 
or in size — the most striking change being a large loss of organic 
matter, while the relative proportions of the phosphate and car- 
bonate of lime remain comparatively unaltered. 
These facts, it is true, are quite sufficient to disprove the truth 
of the theory that the inorganic part is the sole fertilizer in bones ; 
or even that the animal matter is insignificant ; at the same time, 
however, I cannot see that it establishes Professor Johnston's 
own position — that the animal matter is the main and most imme- 
diately beneficial agent. Though we demolish Sprengel's edi- 
fice, we cannot destroy the materials of which it is built. Thus 
we have still before us the fact that 60 per cent, of inorganic 
matter equals in some cases, and surpasses in others, 60 parts of 
the same inorganic matter when combined with 40 of animal 
matter : and this, it may as justly be asserted, proves that the 
animal matter is little worth, as the cases cited by Professor 
Johnston prove that it is most "prominently " valuable. This, it 
may be said, is an anomalous position. We have facts which 
prove the very opposite conclusions. The anomaly is, however, 
more apparent than real. It is not the facts to which we should 
object, but to the use which has been made of them. Thus, the 
evidence given by Professor Johnston only shows that the animal 
* Vide Royal Agr. Journal, vol. v, 
E 
