have broken down and rotted.  This rotting of the tissue, or flesh, of these plants is the great enemy to their cultivation in England.  When it appears, it should be carefully cut out with a sharp knife, and exposed to the influence of a perfectly dry atmosphere for a few days till the wound has dried, when the plant should be potted in a sandy compost and treated as for cuttings.  Sometimes the decay begins in the side of the stem of the plant, in which case it should be cut away, and the wound exposed to a dry air.  The cause of this decay at the base or in the side of the stems of Cactuses is no doubt debility, which is the result of the absence of some necessary condition when the plants are cultivated in houses or windows in this country.

Grafted plants, especially Epiphyllums, when worked on to Pereskia stocks, are apt to grow weak and flabby through the stem wearing out, or through the presence of mealy bug or insects in the crevices of the part where the stock and scion join, in which case it is best to prepare fresh stocks of Pereskia, and graft on to them the best of the pieces of Epiphyllum from the old, debilitated plant.  It is no use trying to get such plants to recover, as, when once this disease or weakness begins, it cannot easily be stopped.

CHAPTER IV.

PROPAGATION.

Cactuses may be multiplied from cuttings of the stems, from seeds, and also by means of grafting; this last method being adopted for those species which, under cultivation, are not easily kept in health when growing upon their own roots, or, as in the case of Epiphyllums, when it offers a means of speedily forming large and shapely specimens.  From seeds the plants are generally freer in growth than when cuttings are used, although the seedlings are longer in growing into flowering specimens than large cuttings would be.  To the amateur, the process of germination and development from the seedling to the mature stage, is full of interest and attraction, the changes from one form to another as the plant develops being very marked in most of the genera.

Seeds.—­Good fresh seeds of Cactaceous plants germinate in from two to four weeks after sowing, if placed in a warm house or on a hotbed with a temperature of 80 degs.  If sown in a lower temperature, the time they take to vegetate is longer; but, unless in a very low degree of heat, the seeds, if good, and if properly managed as regards soil and water, rarely fail to germinate.  For all the kinds, pots or pans containing drainage to within 2 in. of the top, and then filled up with finely sifted loam and sand, three parts of the former to one of the latter, and pressed down moderately firm, will be found to answer.  If the soil be moist at the time of sowing the seeds, it will not be necessary to water it for a day or two.  The seeds should be scattered thinly over the surface of the soil, and then covered with