Opuntia Rafinesquii and var. arkansana, O. vulgaris, O. brachyarthra, O.
Picolominiana, O. missouriensis, O. humilis, Cereus Fendleri, C.
Engelmanni, C. gonacanthus, C. phoeniceus, Echinocactus Simpsoni, E.
Pentlandii, Mamillaria vivipara.

Having briefly pointed out the various positions in which Cactuses may
be cultivated successfully, we will now proceed to treat in detail the
various operations which are considered as being of more or less
importance in their management. These are potting, watering, and
temperatures, after which propagation by means of seeds, cuttings, and
grafting, hybridisation, seed saving, &c., and diseases and noxious
insects will be treated upon.

Soil.--The conditions in which plants grow naturally, are what we
usually try to imitate for their cultivation artificially. At all
events, such is supposed to be theoretically right, however difficult we
may often find it to be in practice. Soil in some form or other is
necessary to the healthy existence of all plants; and we know that the
nature of the soil varies with that of the plants growing in it, or, in
other words, certain soils are necessary to certain plants, whether in a
state of nature or cultivated in gardens. But, whilst admitting that
Nature, when intelligently followed, would not lead us far astray, we
must be careful not to follow her too strictly when dealing with the
management of plants in gardens. There are other circumstances besides
the nature of the soil by which plants are influenced. Soil is only one
of the conditions on which plants depend, and where the other conditions
are not exactly the same in our gardens as in nature, it is often found
necessary to employ a different soil from that in which the plants grow
when wild.