506 
THE PRINCIPLES OF BOTANY. 
as the fiax, hemp, colza, mustard, &c. In the latter and 
some others, fixed and essential oils are both present; this is 
the case with the charlocks and wild mustards, which are 
used with colza or rape for the expression of their oil, but 
as the cake of the mustards after the expression of the fixed 
oil is replete with a strong essential oil death has sometimes 
resulted to cattle from its use. In such cases the veterinary 
surgeon will soon trace the inflammatory action which has 
been set up in the stomach and intestines, and it is a subject 
for the botanist and chemist to point out the nature of the 
food from which it may have arisen. Seeds contain innu¬ 
merable organic bases; thus strychnine, piperine, capsicine, 
crotonine, are the active bases of nux vomica, pepper, cap¬ 
sicum, and croton fruits or seeds, and it is not unlikely that 
such individual plant, and oftentimes the different parts of 
plants have their own peculiar organic bases. These are 
now extracted by the chemist, and so instead of the practi¬ 
tioner being obliged to employ a medicine mixed with its 
cruder particles, some of which may retard the required 
action, he can neatly employ the separated active principle 
which being determinate in composition, whilst in the drug 
it is seldom or never present in exact and uniform propor¬ 
tions, he can regulate his dose with perfect exactitude. 
From the foregoing remarks it will be concluded that 
whether we have seeds for their feeding products, their me¬ 
dicinal value, or simply as reproductive elements, it is worth 
while to study them in all their details. In the matter of 
corn its value and, consequently, the price of each kind is 
regulated by its weight per bushel, the greater weights being 
only obtained by plump, well developed, and well harvested 
seeds. 
With regard to medicinal seeds it is more than probable 
that their value much depends upon the judgment exercised 
with respect to the period at which they should be harvested. 
The value of seed as a reproductive element will depend 
upon a number of circumstances, as full development, weight, 
and freshness. We know farmers who habitually sow thin 
grain; we have, however, found in practice that stout seed, 
though not consisting of so many individuals to a bushel as in 
thin seed, yet a less measure will produce a better crop. 
Some seeds soon lose their vitality, so that as a rule fresh 
seed is to be preferred; but in the case of seeds where birds 
may take some, where the soil may not be suitable, a differ¬ 
ence in climate, cultivation, and management, all may exert 
a different effect upon the result, and thus all afford so many 
loopholes of escape for the nefarious dealer, seed admixtures 
