602 On the Valuation of Unexhausted Manures. 
In a similar manner the productive effects of linseed, linseed- 
cakes, barley, beans, and swedes, each used in suitable admix- 
ture with other foods, have been estimated. Thus, the actual 
and comparative productive effects of a few characteristic foods 
have been approximately determined ; and from these results the 
capacity of allied foods has been estimated, taking into con- 
sideration the relative amounts of digestible and indigestible 
constituents, which the foods to be compared on the average 
contain. It is in this way that the figures in the first and second 
columns of Table II. have been arrived at. It should be stated, 
however, that in the case of the straws no direct experimental 
data were at command, and their productive effects are esti- 
mated mainly on their recorded amounts of digestible con- 
stituents compared with those in hay, and they are more 
probably given too high than too low. 
It is obvious that such estimates can be only approximately 
correct ; but they are at any rate the best that existing know- 
ledge renders it possible to make. It is pretty certain that the 
amounts of increase assumed to be produced are higher than 
those usually obtained. The amount estimated to be yielded by 
linseed-cake, for example, is certainly higher than would be 
obtained, when, as is sometimes the case, it is given in such 
excessive amount that much is voided by the animals undi- 
gested. On the other hand, the amounts of the different foods 
estimated to be required to give 1 part of increase are doubtless 
higher than would be so required, if as large a proportion of the 
constituents were digested and utilised as have been shown to 
be digestible in the German experiments on that subject. In 
those experiments the animals were for the most part kept on 
mere sustenance food, so that they would digest the maximum 
proportion of the constituents they received. In the case of 
fattening, however, especially with early maturity, the condi- 
tions are very different. The animal receives a greater or less 
excess of food, and not only voids proportionally more un- 
digested, but may transform more than is fully utilised. It is, 
nevertheless, economy to give an excess within certain limits. 
The apparent waste is, in fact, more than counterbalanced. 
Thus, in the first place the manure-value of the not utilised 
food still remains intact ; but the real source of the economy 
is in the shortening of the time of feeding, and so, at the 
cost of some excess of food, saving the amount that would be 
expended in the mere sustenance of the animal for a longer 
period. 
Trusting that, with these explanations, the figures will not be 
misunderstood, we may proceed to the consideration of the rest of 
the Table, only further remarking in regard to the estimates in 
