EFFECTS OF SOIL AND CULTIVATION ON PLANTS. 211 
The circumstances which I proposed to consider, as affecting the medicinal 
value of a plant, are:—mutilation, when giving rise to an unnatural develop¬ 
ment of particular parts ; effects of soil, as indicated by the chemical analysis 
of the soil and plant; and situation, with reference to the supply of air, light, 
and moisture. 
The principle of mutilation is not generally practised, although by sup¬ 
pressing the development of flowers, a larger number of leaves may be 
obtained. In the case of the Labiatse, we may by suppressing the develop¬ 
ment of wood, produce a larger quantity of oil, but it does not appear that 
by the mere removal of leaves, a larger quantity of oil is obtainable, more 
flowers are developed, but the yield of oil is proportionally diminished; this 
might possibly admit of explanation, from the importance of the functions 
which the leaves perform in regulating evaporation and supplying air, the 
main features in the elaboration of the vegetable fluids. 
Mutilation will not in every case account for the non-development of an}^ 
particular organ or part of a plant. 
I planted about three years ago, but without determining the suitability 
of the soil, several slips of rosemary: they have all put out abundance of 
shoots and leaves, but the number of flowers has been very insignificant; no 
mutilation has ever taken place. At the same time I laid out several plants 
of lavender, which became completely exhausted after the second year, and 
out of forty slips planted at the same time, not one struck ; this, I have since 
discovered, may be explained by the chemical condition of the soil (see analysis 
in Appendix), and the physical requirements of the plant. 
Non-mutilated lavender plants yield considerably finer flowers, when grown 
on a suitable soil, but the quantity is much less than from plants in which 
the development of wood is prevented, and the yield of oil is greater in the 
latter case; the same remark applies, though less forcibly, to peppermint 
and rosemary. 
The injudicious mutilation of lavender plants, explains to some extent the 
great differences in the yield of oil obtained by different growers. 
Mutilation, when practised, should be regulated by the season and expo¬ 
sure of the plant. 
I am strongly of opinion that mutilation is not confined to the Labiatse, 
although I hesitate to include the result as arising from mutilation, rather 
than an indication of hybrid development; but it is a singular fact, that 
henbane plants, when cultivated, show a tendency to capitate inflorescence, 
whereas the same plants (self-sown) are strongly disposed to a racemose 
arrangement of its flowers, and in this case an enormous yield of flowers is 
produced compared with the quantity of leaves. The cultivated plants indi¬ 
cate more or less an axillary inflorescence, and the capitate disposition should 
perhaps be regarded as arising from an abortive development of the stem. * 
My experiments on henbane were far advanced when I first observed this, 
as it was only after flowering that I distinguished any difference in the plants. 
In the case of plants, when the unexpanded flowers are gathered, as roses, it 
would be very desirable to cletermine.whether any difference exists in the medi¬ 
cinal value of the flowers first collected during the season, and those which 
are gathered near the end, for it is evident that this imposes no less on the 
energies of the plant, than mutilation in the general acceptation of its prin¬ 
ciple, and I hope to return to this inquiry at an early period, to determine 
the difference, if any, which arises through the gradual though unavoidable 
exhaustion of the plant. 
I have performed an extensive series of experiments on this point, to deter¬ 
mine whether such plants as belladonna, foxglove, and henbane should be 
allowed to perfect their flowers or seeds before the leaves are collected for 
