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NEW AND RARE PLANTS. 
systems of organs, devoted to special purposes. But in plants, when we except the reproductive 
organs, all the rest of the plant is composed of distinct cells or elementary parts, each a little chemical 
lahoratory in which arc composed the substances out of which new productions of form are to be 
constructed : and cells having- the same office (with the exceptions of those in the reproductive organs 
where there is great variety), may be said to ho alike in all plants. Thus, for the study of physiolo- 
gical botany, it is by no means necessary to be acquainted with all the varieties of general form and 
their morphological relations so infinite in the vegetable kingdom : all we require is, an intimate 
acquaintance with the characters of the elementary tissues in general, and, in a given inquiry, of their 
peculiar arrangement and distribution in the particular plant whose life we arc engaged in observing. 
For a thorough comprehension of vegetable physiology, it is indispensihle to possess an intimate 
practical acquaintance with the microscopic anatomy of plants ; and had such been possessed by many 
who have laid down laws which have had wide acceptance, those now pursuing the science would have 
been spared many contradictory and bewildering statements, taken up at first on what is supposed 
sufficient authority, and only rejected after long and painful investigation, which might have been 
better employed in independent inquiry, setting out from the lower point at which our positive 
knowledge actually stands. It should be a rule with every vegetable ph3'siologist to believe himself to 
know only what he himself has actually seen. Of course, he must not cast away the help of others, or 
lightly disregard the accumulated treasures which descend to him from his predecessors : but these 
things must always be taken on qualified trust, as tilings to be tested by his own experience, and, on the 
other hand, as tests of his own accuracy of observation. On the one hand, unless he has investigated 
and weighed then- value practically, ho has no right to use the theories of others as data for his own 
reasoning ; and, on the other hand, he must not be led to reason from observations of his own, to 
conclusions that involve contradictions of facts observed by others, until he has made a thorough and 
complete examination of the grounds upon which these facts have been stated. The great rule to be 
observed, and that which will enable every one whose occupations take him daily among living plants, 
to furnish valuable material to science, is to limit his reasoning to the conclusions legitimately deduoible 
from the facts that he lumself observes. Thus, supposing a person to make a series of measurements of 
the growing stems and branches of different trees, at various seasons of the year, it is no business of 
his, and can be of no value to science, to argue about the movements of the sap, on the grounds of the 
increase of size, unless he has also practically examined the internal structures, and can demonstrate 
a relation between their changes and those of the external form. He may speculate if he will, and such 
speculations may be useful as such, and lead to inquiry, but such a proceeding does not add to our 
positive knowledge, and we must always mark very broadly the difference between " it may bo so " 
and " it is so." 
These points have been thus largely dwelt upon because there is such a mass of speculation included 
as knowledge in all works on physiological botany, and because wc really know so much less than is 
commonly imagined. They have been dwelt upon in the hope of impressing the necessity of direct, 
practical, and above all, cautious examination of facts, so many of which tall within the daily experience 
of horticulturists. With the exception of a few great names, the chief writers upon vegetable pin sic ill igj 
have had but imperfect opportunities of observing living nature day by day, with that close attention 
and comprehensive view winch is requisite to sound generalization. Most of those who have written 
general treatises upon the subject, have been dependent on the relation of others for the great body of 
their information, and, Unfortunately, have been only too prone to draw general conclusions from these 
second-hand ideas, without a sufficient practical criticism of them. 
In making the foregoing statements, I have anything hut a desire to east blame upon the intentions 
of others; and, indeed, in here writing upon the subject, I lie inevitably exposed to fall into the very 
same error. They are rather given with a view to explain the sceptical character which u ill probably 
be manifest in some of the succeeding papers, and direct attention more forcibly to the imperfect and 
Unsatisfactory stale in which this department of the science lies, in the hope of stimulating the activity 
of those who have an Opportunity of adding to our knowledge, and, at the same time, of impressing the 
absolute necessity of extreme caution and self-denial in following out our hypotheses, if we wish to 
Contribute anything really valuable and permanent to the general fund of positive science. 
jiJriu miu Era plants. 
Oiinitiiarium btriattjlum, Lindloy. Streaked flowered Oraitharium [PaxU VI. Qard., i, 188). — Nat Ord., 
OrchidacctB § VandetB-SorcanthidiB. Syn., Ornithochilus striatums, «/"'/« Calcutta Garden. A stove epiphyte 
of little beauty. It has two ranked pale green leaves, notched ;it the end, and axillary spikos of small, waxy 
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