It would be very difficult to find any plants in the whole vegetable kingdom which present such beautiful examples of symmetry as the mamillarias, and in their own family they are also unique in this respect, for though many of the grotesque opuntias, cereuses and echinocactuses possess larger and more brilliant flowers, and they are surpassed in horticultural value by the phyllocactuses and epiphyl-lums, yet for delicacy of design they are unrivalled. A large number of them resemble exquisite pieces of mechanism finished with the greatest minuteness and accuracy. Others, again, might be imagined to have undergone a kind of crystallization, their whole surface being frosted over with star-like spiculae arranged with geometrical precision; and still others appear as if covered with the finest gossamer.

Culture

Many of the mamillarias are found in limestone districts, and though inhabiting varying climates and elevations, they may be all grown in an intermediate temperature, such as a greenhouse, where they can be protected from frosts during the winter, but a higher temperature is needed during the spring and early summer when growth is advancing. A free exposure to light and sun is requisite at all times. The soil should consist of two-thirds sandy loam and one-third finely broken bricks and lime rubbish. The pots must be well drained, and water should always be carefully supplied, but much injury is often done by keeping the plants too dry. They should be examined at least once a week, even in the winter, and if the temperature is above 500 and the weather bright they may be safely watered. These plants may be advantageously grown in a glass case, as this protection keeps the dust from their beautiful spines.

Propagation

The majority of the tufted and branching species can be readily increased, either by the offsets from the base, or by removing the side branchlets. The former only need potting like ordinary plants, keeping them rather dry until growth commences. The branchlets can be laid upon dry soil until some roots show at the base, and they can then be treated similarly. The more delicate sorts, or those that produce few offsets, can be grafted on any of the cereuses, to which they readily unite ; and this has a double advantage, for while the plants often grow more strongly, they are also less liable to decay, as such forms will do unless very great care is exercised in supplying water. Cereus tortuosus and others of slender habit may be chosen for the small-growing species. - Lewis Castle.