158 
ROYAL HORTICULTTTRAL SOCIETY. 
as also from the fact that they apply to the cultivation of all or any 
plants, they seem worth constant attention. 
To ensure the successful culture of any plant, and to gain the 
greatest possible advantage from it, its whole life-history, from 
germination to death, should be as thoroughly known as possible. 
Without such knowledge cultivation must be empirical ; and 
although under one set of circumstances such cultivation may be as 
successful as could be desired, yet the grower would be at fault 
in the event of the occurrence of adverse conditions. Possessed 
of such knowledge the cultivator can do much to remedy any 
evil which may arise, or make compensation for its effects. At the 
worst he knows its extent. 
Scarcely less important than a knowledge of the mode of life of 
the plant is an acquaintance with the circumstances causing modi- 
fications in it. Among these latter points may be mentioned the 
physical and chemical characters of the soil, — both important, the 
former specially so — always presuming there be no excess of hurt- 
ful ingredient in the soil and no absolute deficienc}^ of essential 
elements therein. 
The effects of temperature and moisture have already been 
referred to. All that I would allude to now, in reference to 
climatal vicissitudes, is the importance in such inquiries as those 
now under consideration of considering the time at which the 
changes take place, and the special work which the plant is doing, 
leaf-, flower-, or seed-making, at that particular period. 
Another point which strongly impresses itself in working out 
the results of the experiments is the advantage that is derived 
from an admixture of manures. In hardly any instance did 
mineral manures, or nitrate of soda, or ammonia salts, when applied 
by themselves, produce any thing like the same amount of vigour 
as was produced by an admixture of mineral manures with ammonia 
salts or with nitrate of soda respectively. These are points which 
will probably be dealt with by the more experienced hands of Dr. 
Gilbert, who has charge of the chemical points concerned in these 
inquiries. 
Lastly may be mentioned the circumstance which repeated 
observations seem to justify, viz. that certain plants prefer to grow 
in association with others rather than by themselves. This was 
noted, especially in the case of the vernal grass, Anthoxanthum^ 
which made very unsatisfactory progress whenever grown by itself. 
A similar circumstance, though less marked, was observable in the 
case of the Dutch Clover, Trifolium repens. 
