76 PATTERSON v. M'CAUSLAND.—3 BLAND.

to have been collected into bundles; or to have undergone some
peculiar inflexions as the tree advanced in age. We know that,
here, roses do not bloom in January, that apples do not ripen so
early as April, nor cherries so late as October; and we also know,
that some forest trees bring their fruit to maturity annually, and
others only biennially; that some trees are of the moncecia class,
having the male and female organs on the same tree, and that
others are of different sexes, or of the divecia class, having the
males and females in distinct trees. These peculiarities, and
the periodical fructification of trees being known, as in the case
of the known terms of the incubation and gestation of ani-
mals, the law respects and confidently relies upon such a known
regular course of nature. But no series of observations, by
botanists or cultivators, have as yet demonstrated that any
portion of the wood of a tree, as visible to the naked eye
on dissection, was, like its fruit, the result of successive pe-
riodical formations, known to have been made within cer-
tain spaces of time, nor have philosophers, with the aid of chemis-
try or the microscope, been as yet able, in this and a multitude of
other particulars, to detect the latent operations of the vital prin-
ciple in vegetation; leaving all questions as to its gradual or periodi-
cal progress, still covered up in the most impenetrable obscurity.
Thompson's Chew, b. 4. c. 3; 11 Westm. Revw. art. 8, p. 97; Vegetable
Physiology and Arboriculture; Roget Anim. and Veget. Physi. pt. 1 c.
1, s. 2 and 3, pt. 2, c. 1. (i)

(i) "We know the substances received by plants, and those which they
reject; we determine by analysis the nature and the composition of the pro-
ducts which they form; but this is the utmost extent of our knowledge.
All that passes within the plant is still a mystery, and belongs to the laws
of vitality, which modify by their action those physical laws that are known
to us.' —Chaptal's Chemistry applied to Agriculture, c. 5, art. 6.

" Plants may be considered as a set of machines fay which the common
elements of nature are worked up into such a form as to be fit for the sus-
tenance of animal life. We have already examined the structure of this
machine; we will now direct our attention to the way in which it operates.
In this department of the science, the difficulties which the philosopher has
to overcome are of a very different character from those which may have
embarrassed him, in merely determining the organization of the plant. In
the latter case, good microscopes, manual dexterity in preparing the parts
for examination, and sufficient patience for his task, are sure to bring the
observer to conclusions, the general truth of which is often susceptible of
exact demonstration; but when we come to consider the causes of vital phe-
nomena, and the manner in which they are brought about, we have obstacles
of quite another kind to overcome. There is not a function of vegetable life
which is not performed, as it were, behind a screen; the parts which are the
prime movers in every operation, are so minute as to escape our view until
they have been killed for microscopic examination—fixed to the soil, desti-
tute of passions and sensations, the visible expressions of which might lead
us to the discovery of their visible causes—having the whole of its organic