language, is known as the cotyledon stage of development, will be seen;
a month afterwards, this will have assumed the shape of a very small
Cereus. It is interesting to note how the soft fleshy mass which first
grows out of the seed is nothing more than a little bag of food with a
tiny growing point fixed in its top, and that, as the growing point
increases, the food bag decreases, till finally the whole of the latter
becomes absorbed into the young stem, which is now capable of obtaining
nourishment by means of its newly-formed roots.

[Illustration: FIG. 5.--SEEDLINGS OF OPUNTIA, SHOWING MODE OF
GERMINATION. (Magnified three times).]

In the genus Opuntia, the cotyledon stage (see Fig. 5) of the plant is
different from that of the Cereus, and is more like that of a cucumber.
Still, though the form is different, the purpose of the two cotyledons
and the juicy stem in the seedling Opuntia is the same as in the Cereus;
and, as the growing point develops, the cotyledons shrivel up and fall
off, the plant food they contained having passed into that part of the
young seedling which was to be permanent. The seedlings of these two
genera serve as an illustration of the process of germination from seed
of all the Cactuses; and it must be evident that there is much that is
singular and full of interest in raising these plants from seeds. As
soon as the seedlings are large enough to be handled, they may be
planted separately in small pots, using a compost similar to, but
slightly coarser than, that in which the seeds were sown. The soil
should be kept moist till the summer is over; and after that, till the
return of warm sunny weather, it will be found safest to keep the
seedlings on the dry side, a little water only to be given at intervals
of a week, and only when the sun is shining upon the plants.