ely rigid manner. In the practice of
agriculture, plants are placed in artificial circumstances, and instead
of allowing them to depend entirely on the soil, they are supplied with
a quantity of manure containing all the elements they require, and if it
be used in sufficiently large quantity, the same crop may be grown year
after year. And accordingly the order of rotation, which is
theoretically the best, may be, and every day is, violated in practice,
although this must necessarily be done at the expense of a certain
quantity of the valuable matters of the manure added, and is so far a
practice which ought theoretically to be avoided. In actual practice,
however, the matter is to be decided on other grounds. The object then
is, not to produce the largest crops, but those which make the largest
money return, and thus it may be practically economical to grow a crop
of high commercial value more frequently than is theoretically
advantageous. In such cases the farmer must seek to do away as far as
possible with the disadvantages which such a course entails, and this he
will endeavour to accomplish by careful management and a liberal
treatment of the soil.

But while this system may be adopted to some extent, it must also be
borne in mind that the frequent repetition of some crops cannot be
practised with impunity, for plants are liable to certain diseases which
manifest themselves to the greatest extent when they have been too often
cultivated in the same soil. Clover sickness, which affects the plant
when frequently repeated on light soils, and the potatoe disease and
finger and toe have been attributed to the same cause. Whether this is
the sole origin of these diseases is questionable, but there is no doubt
that they are aggravated by frequent repetition, and hence a strong
argument in favour of rotation. It has been asserted by great
authorities in high farming, that with our present command of manures,
rotations may be done away with; but this is an opinion to which science
gives no countenance, and he would be a rash man who attempted to carry
it out in practice.

CHAPTER XIV.

THE FEEDING OF FARM STOCK.

The feeding of cattle, once a subordinate part of the operations of the
farm, has now become one of its most important departments, and a large
number of minute and elaborate experiments have been made by chemists
and physiologists with the view of determining the principles on which
its successful and