April 29, 1871.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
8G1 
VARIABILITY IN THE ACTIVITY OF 
LEAVES. 
BY M. C. COOKE, M.A. 
It is well enough known that the parts of plants 
collected for pharmaceutical purposes are subject to 
considerable variation, that they are by no means 
uniform in the proportions of their constituents, and 
hence are sometimes likely to fail. Many instruc¬ 
tions have from time to time been given for the col¬ 
lection of roots, rhizomes, bark, etc., in order that 
uniformity might be more readily predicated. The 
plant just before the period of flowering is, in many 
of its parts, stronger or weaker in certain consti¬ 
tuents than at other periods. Of all parts, perhaps, 
roots require the greatest care as to the time at 
which collected. Next in order, as it seems to us, 
are leaves. There are not many leaves of indigenous 
plants that are of much importance as articles of 
materia medica ; but there are a few, and if these 
few are to maintain their position, it is of the utmost 
importance that they should be uniform in their 
action, which cannot bo the case if no regard be 
paid to certain facts associated with plant life. 
It may be asked with reason, is there any season 
or any condition which so influences the develop¬ 
ment of active principles in the leaves of plants as 
materially to affect their value as remedial agents ? 
Undoubtedly there is, but not so much affecting cul¬ 
tivated as wild plants, because in the former the 
conditions are more uniform. Setting aside all 
question about periods of flowering or fruiting, or, 
in fact, of any period in the history of any individual 
plant, there seems to be one very important influ¬ 
ence which is very much ignored, as affecting con- 
O 7 O 
dition. This may be illustrated by reference to an 
example in which active principles are developed 
hi a liigh degree, and in which the opportunity for 
testing is easily secured. The facts which seem to 
manifest themselves clearly and unmistakably in 
tobacco leaf, may be supposed to influence bella¬ 
donna leaves, stramonium leaves, and even the 
leaves of other plants not in the least allied to them. 
It is admitted that tobacco grown in a cold cli¬ 
mate is much stronger than that grown hi a mild 
one. In other words, active principles are more 
concentrated hi leaves grown in cold climates, where 
the vegetation is less vigorous, than in warm ones. 
When the tobacco plant is forced on to a rapid 
growth, with a plentiful supply of moisture, the leaf 
is found to contain less of its characteristic prin¬ 
ciples than when stunted, starved, and but slowly 
developed. 
Not only is this true of tobacco, but it is true also 
of other plants which have been tested. It is true 
of cultivated celery that the petioles and leaves are 
much more strongly flavoured when grown slowly 
than when grown rapidly, and under favourable con¬ 
ditions of soil and moisture. Except as they influ¬ 
ence rapidity of growth, it is very doubtful whether 
the chemical constituents of a soil affect in any ap¬ 
preciable degree the active principles of leaves. 
Take another example, although not, perhaps, 
quite so pertinent. In a • very dry season, or when 
growing in very dry localities, the leaves of the 
common nettle are much more highly charged with 
their irritating poison than when grown rapidly, in 
a wet s.eason, or in a moist locality. 
From these and similar instance?, therefore, we 
are led to the conclusion that rapid growth, with a 
Third Series, No. 44. 
plentiful supply of moisture, is least favourable to 
the development of those properties in leaves which 
are of value in medicine. Whether tins principle 
holds good with glandular plants, secreting essential 
oil, such as the Labiatce, we are not prepared to 
affirm from actual experience. The inference is, 
that leaves ’grown in a dry season would, ceteris 
paribus, be more active than leaves grown in a wet 
one ; that plants grown in a damp situation or a 
rich stimulating soil would be milder than those 
grown under less favourable conditions. In fact, we 
have found the leaf of Arum maculatum to vary con¬ 
siderably in its biting acrid properties in proportion 
to its development. Leaves from large rapidly grow¬ 
ing plants in moist situations are by no means so 
acrid as the small leaves of stunted plants growing 
on dry banks. This is an experiment which any 
one can perform for himself during a country stroll. 
It would be of interest to ascertain by careful 
analysis what is the difference in the proportions of 
the constituents of such leaves as belladonna and 
stramonium, grown under the two conditions of vi¬ 
gorous and retarded vegetation. The very rough test 
applied to the leaves of arum, and the inexact one 
applied to tobacco, indicate strongly enough that 
there must be a very appreciable difference ; but this 
is in itself insufficient, it should be determined what 
is the difference; and we have no doubt it will bo 
sufficient to account for much of the variability in 
the action of leaves. 
A less important circumstance, but one which 
should not be lost sight of in this connection, is the 
difference between fully matured and young leaves 
from the same plant. There can be no doubt that 
there is a difference, but the proportion of young- 
leaves, weight for weight, to mature leaves will not 
be great when dried, because the larger percentage 
of water in young leaves will reduce the dispropor¬ 
tion, as well as the excess of mature leaves which 
will be collected from a full grown plant, over im- 
matured ones. 
From these suggestions it seems to us that the 
pharmacologist may collect some of the causes that 
influence the variability in activity of leaves gathered 
and dried indiscriminately. It is quite possible that 
in some instances foliaceous drugs have been con¬ 
demned for their uncertainty, when the fault has 
really been traceable to an unsystematic and indis¬ 
criminate mode of collection. The results of re¬ 
cent experiments on the influence of climate, soil, 
moisture, and other external circumstances, upon the 
development of active principles and aroma in to¬ 
bacco leaves, incline us to the opinion that, not only 
in that instance, but in many others, the circum¬ 
stances and their influences have been too much 
forgotten or ignored. With tliis impression we have 
ventured to direct attention to the subject, in the 
pages of a journal which is interested more than 
any other in pure and uniform drugs. 
Vinca Major. —Mr. Spencer Wells states that in 
some cases of menorrhagic bleeding he has found a pre¬ 
paration of Vinca major , the well-known Greater Peri¬ 
winkle ©f our shrubberies, preferable to lime,, gallic 
acid or ergot. He was first told of it by Mr. Squire, and 
has prescribed it according to the formula given in that 
gentleman’s 1 Companion to the British Pharmacopoeia, 
viz. an infusion of 2 ounces of dried herb to 20 ounces of 
boiling water, and strained when cold.— British Medical 
Journal. 
