plants referable to different families will not graft on each other, apparently, because the juices
elaborated in different families of plants, though growing side by side, in the same soil, are so
different in their qualities that those of the one are unfit to nourish a branch taken from the
other: while on the other hand two plants of the same natural family, however much the soils
in which they respectively grow may differ, can generally, be readily grafted on each other. From
the same cause, the action, namely, of organization on secretion, we find in a great, many instances
identical properties common to whole families of plants. Acrimony predominates
throughout the Ranunculaceae and Cruciferae: narcotism is the characteristic of Papavera-
ceae and Solanaceae: Apocyneae are generally poisonous and some of the species most virulently
so: astringency is common to nearly all the arboreous Mimoseae as well as to many of the
Caesalpineae, it equally predominates in Terminaliae, and the whole of the genus Quercus is
pre-eminently marked by that property. The Cucurbitaceae, Convolvulaceae and Euphor-
biaceae are equally distinguished by properties the very reverse, the action of many species of
each of these orders being violently drastic. The fruit of Rosaceae and seed of Leguminosae
on the contrary, are so universally wholesome that it may be laid down as a general rule almost
without exceptions, that they may be safely partaken of whenever they are met with.
These few examples will suffice to show how vastly the study of properties is facilitated by
an acquaintance with natural affinities, and will, I trust, at the same time serve to remove an
objection which I have more than once hard urged against this work, that it did not sufficiently
treat of Medical Botany. This objection could only be raised by those who did not sufficiently
consider that its object was to establish principles on a scientific basis, as being the true way to
attain the object sought for. There is no royal road to science, and until the medical man
studies the principles of Botany as a science, he need never expect through an inspection of
plates or specimens of medical plants to become a medical Botanist. But with only an elementary
knowledge of Botany, such for example as a perfect knowledge of the structure of the flower and
fruit, an acquisition not generally of very difficult attainment, the case is widely altered, since any
one who had advanced so far in the knowledge of the elements of the science may easily make
himself master of the characters of a few species of an order, and then he can generally trace its
relations with nearly allied orders or even recognize some of them from family likeness alone.
Having ascertained the order of the plant under examination the subsequent steps leading to the
attainment of a comprehensive knowledge of its name, history and properties, are comparatively
easy; andnot of it only but of the whole order. It is true, that to acquire a thorough acquaintance
with an order, frequently requires the student to examine and carefully compare several, but every
plant so examined facilitates subsequent researches and lessens the difficulty of the next step,
that namely of making .out the genus. But even without going so far, having once-determined
the order of a plant, we are in possession of a fund of information, since, but little further trouble
is required to make ourselves acquainted with all that is yet recorded respecting that order, and to
ascertain whether any applications we have learned are still unknown to science. The natural
method in short gives both precision and extension to any enquiries we may undertake respecting
plants, whether considered with reference to organic structure and its modifications, the products
of organic life in connection with structure, or the applications of these products to the
comforts and conveniences of life; and thereby to the advancement of civilization among men.
The difficulties to be surmounted at the outset of the study are no doubt often great, those namely,
of determining the order of a plant when it departs from the normal structure of the order to
which it belongs; but even then, a futile search is not unattended with advantage, as the examination
puts us in possession of much useful information which will materially assist our future
research should we be necessitated to turn to the artificial system to find its name.
Should we on the contrary commence our examination with the artificial sexual system the
first step, that of determining the class and order of a plant is the easiest, but that done, it often
happens that nothing is learned, for, should the specimen under examination have a stamen or
style more or less than the regular number, and nothing is more common among tropical plants,
we look in vain in the class or order where according to our specimen it should be found, and
when found, still that system» conveys no collateral information regarding the relations of the
plant or of the nature of the properties with which it may be endowed.
In drawing these comparisons it is not my wish unduly to exalt the one at the expense
of the other, for in truth they are so very different that it is impossible to compare them,
they both have their advantages and disadvantages, and in the present state of the science
are both necessary, I certainly think however the preponderance of good is greatly in favour
of the natural method. In thus giving the preference to that system which enables the student,
who has made considerable progress in its study, to look over a large collection of plants, not
one of which he had ever seen before, and readily refer probably as many as 19 out of every
20 to its proper natural order, from family likeness alone, I am far from as yet wishing to see
the other altogether exploded, since by it we are often enabled quickly to determine abnormal
plants that we could not so easily have done by the other; and in such cases, I still occasionally
find the advantage of having formerly become familiar with the Linnaean system. Though to
this extent I approve of it, I could not recommend it for general use, as its natural tendency
is to contract our ideas by concentrating our attention too exclusively on one set of organs
and confining our enquiries to the investigation of the pames of species only, in place of, as is
the case with the other, expanding them with the growth of our knowledge by extending our
researches, from the examination of species to the investigation of masses in all their bearings.
While for these cogent reasons, we are in the present advanced state of the science gradually
permitting that once celebrated system to drop into oblivion, we must not forget how much
Botany is indebted to it for its present advancement. The extent of these obligations can only be
justly appreciated by comparing the Botanical works of its great author with those of his immediate
predecessors, not one of the plants described by whom can now be made out from their descriptions
unaided by some collateral circumstance or by plates and too often, even with these aids,
they are still unknown. Immediately on its introduction into practice order supplanted disorder,
arrangement and method succeeded and dispersed the previous confusion and perflexity
as light disperses the darkness. From this hour materials accumulated with unprecedented
rapidity and have continued to do so to such an extent, that the catalogue of known plants
which on the most liberal computation, did not at Linnseus’ death exceed 12,000, is now but little
if at all short of 100,000 species. To this increase the natural method owes much of its present
admirable precision, as without such a mass of materials innumerable breaks in the chain of
affinities must still have existed, marring both its beauty and usefulness. We may thence I .
think fairly conclude, that the sexual system of Botany, however defective in scientific precision
and comprehensiveness of design, was yet of incalculable benefit to the science, the im