212 
BllITISII PHARMACEUTICAL CONFERENCE. 
the preparation of medicinal extracts. I find that the amount of active prin¬ 
ciples contained in the leaves, remains the same both before and immediately 
after flowering; it is slightly diminished in the stalks and roots after the fall 
of the flower, and gradually accumulates in the remaining appendages of the 
flower. 
The maximum accumulation in the seeds and seed-vessels of foxglove and 
stramonium, I have found to be attained before the seeds change their colour. 
In the case of belladonna, this is not so strongly marked as in foxglove, 
henbane, or stramonium. 
With good specimens of foxglove recently collected, it is easy to obtain 
the colour reaction of digitaline, by simply moistening the seeds with dilute 
sulphuric acid. 
These experiments have been confined entirely to the biennials, in some 
cases transplanted so as to be within easy access. 
Although I have closely studied the effects produced by cultivation, and 
have prepared several artificial soils to determine the effects produced by dif¬ 
ferences of mineralizing ingredients, I regret that the information which may 
be deduced from my experiments is so limited. This is necessitated by the 
fact,, that it is not easy to detect any differences in the mineral composition of 
the juices of a plant, which may be raised on soils having a slight difference 
in their mineral constituents; and since time is required for the indication of 
a maximum effect on the chemical constitution of a plant, and the degree cf 
acceleration with which such effect is produced, and as my experiments have 
been limited to a single year, it is not right to infer that the results indicated 
form the totality of what might under the continuation of the experiment be 
expected. 
There can be no doubt that the continual raising of medicinal crops upon 
any soil, without supplying the same with manure in some form, must be fol¬ 
lowed by an alteration in the chemical constituents of the plants ; such effects 
can be determined only by experiments extending over three or four years. 
Prom the information which I have been able to gather, it is quite probable 
that the careful application of manure to medicinal crops is of essential im¬ 
portance, and that merety restoring the saline matter to the soil which had 
been extracted during vegetation will not maintain its productive capacity. 
Most growers with whom I am acquainted adopt the principle of rotation, 
but the most experienced prefer supplying their land with rich stable manure 
after each crop. The principle of rotation is ultimately exhaustive, but by a 
judicious combination of both principles better crops are obtained, both in 
quantity and quality. 
Plants which are disposed to h} r bridity should be frequently renewed from 
the seeds of the wild plant; in general, the appearance of medicinal plants 
under cultivation, as far as my opportunities have extended, show a decided 
absence of hybrid species. This, I think, is produced by selecting for propa¬ 
gation such plants which are symmetrical in their physical and botanical 
development. 
I have been informed that the parings of horses’ hoofs is, or was, exten¬ 
sively used at Mitcham for lavender and peppermint crops, and although 
they certainly contain a considerable quantity of phosphate of lime and nitro- 
genized matter, it is difficult to understand their suitability as a manure, un¬ 
less, irom their slow and gradual decomposition, the soil is kept in a more 
uniform condition for a much longer time. I have not been able to determine 
the absolute value of this dressing for oil-yielding crops, but as far as its ap¬ 
plication for producing lavender flowers for “ bunching,” it seems eminently 
suited. The grower wffio used this to the greatest extent did not cultivate 
lavender for distillation. 
