CHAP. C.

tnrriCA'CE®. j/o'rus.

1357

spirits, the gum having been dissolved by the spirit The whisk is then moved lightly about tillthe filaments adhere to it, and are drawn off. As soon as a sufficient number are collected, thereeling begins. (See Amer. Silk-Grower's Guide , Murray on the Silkworm; Nouv. Cours d'Agric., & c.)If well fed, in a proper temperature, the caterpillars will have finished their labours in 24 days fromthe period of being hatched; and the quantity of silk produced will, other circumstances beingequal, be in proportion to the quantity of food devoured: its quality will depend on the climate andsoil in which the leaves have been grown. An ounce of eggs will produce about 40,000 caterpillars,which will consume 1073 lb. of leaves, and produce 80 lb. of cocoons, or about 8 lb. of raw .silk. Theworms are subject to numerous diseases, the most fatal of which is vulgarly called the tripes; andis brought on by wet or improper food. When any insects appear sick, they should be immediatelyremoved from the rest, as all their diseases appear to be contagious- Wet leaves should never begiven to silkworms, as they occasion disease ; and it is better to let the insects fast for 24 hours,or even longer, than to give them leaves that are not perfectly dry. In wet weather, the branchesof the tree should be gathered, and hung up in a dry place; or the leaves should be gathered, andspread out to dry. {Nouv. Cours d'Agric., vol. xvi. p. 103.)

Substitutes for Mulberry Leaves in feeding the Silkworm. It is probable that the leaves of all theplants that contain a milky juice will, if they are eligible in point of texture, afford suitable foodfor the silkworm, from the common property of milky juice, that of' containing caoutchouc.Accordingly, trials have been made with the tender leaves of the fig, with the leaves of the maclura,and of A'cer platanbides and A. tat&ricum, among trees; and of lettuce, endive, beet, spinach, nettle,&c., among herbaceous plants. None of these substitutes, however, are of any real use, unless weexcept the maclura and the lettuce. The former, according to the American Gardener's Magazine ,is thought likely to answer to a certain extent; as the lettuce and endive have done formerly, moreespecially when the plants have been allowed to send up their flower stalks before their leaves weregathered. In 1792, a Miss Croft of York sent a specimen of silk of her own rais'ng to, the Society of Arts , the worms producing which had been fed entirely on lettuce leaves.

Soil, Situation, Propagation, and Culture. The white mulberry is moretender than .Mdrus nigra, and requires more care in choosing a situation forit. Calcareous soil is said to produce the best silk; and humid situations, orwhere the roots of the tree can have access to water, the worst. A gravellyor sandy loam is very suitable; and trees grown on hilly surfaces, and poorsoils, always produce superior silk to those grown in valleys, and in richsoils. The tree is propagated by seeds, cuttings, layers, and grafting. Toobtain seeds, the berries must be collected from trees which have beenknown to produce male catkins the preceding spring. The berries areeither gathered when quite ripe, and left to become dry before the seedis separated from them; or they are put into water as soon as gathered,and rubbed so as to separate the seeds, which are cleansed from the pulpin the water, and then rubbed dry on a linen cloth, and either sown im-mediately, or mixed with sand, and kept till wanted for use. In the southof France , the seeds are sown as soon as the fruit is gathered, and the plantscome up the same autumn ; but, in colder climates, they are kept till spring,when they generally come up in three or four weeks, and require some pro-tection, at first, during cold nights. In Germany , and in the north of theUnited States , the young plants are covered, during the first winter, with dryleaves or straw; and this covering, or mulching, is continued on the groundfor three or four years, till the plants are thoroughly established, to protecttheir roots from the cold. The young plants are generally taken up andreplanted the second spring, care being taken to place them in rows 4 ft.asunder, for the convenience of gathering the leaves. M. a. multicaulis is alwayspropagated by layers or cuttings; the layers being made in spring or at mid-summer, and separated from the mother plant in autumn ; or by cuttings ofbranches, or truncheons, which will root readily, and produce leaves for theworms the following year. Count Dandolo recommends grafting the specieswith the large-leaved varieties, near the ground, the third spring; but mostwriters on the silkworm appear to prefer seedling plants, or plants raisedhom layers or cuttings, to grafted ones. In pruning, cutting in, or headingdown, the trees, the great object is to preserve the equilibrium of the heads,so that the sap may be equally distributed through the branches on everyside. On this depends the production of a crop of leaves of equal quality onevery part of the tree, which is alike important both for the first crop, whichis given to the worms, and for the second crop, which is required for thenourishment of the tree.

. Insects and Diseases. The leaves of the white mulberry are eaten by nomsect but the silkworm : it is, however, attacked by numerous diseases, partly,no doubt, occasioned by the unnatural manner in which it is treated, by beingstripped of its leaves. One of these diseases is brought on by any sudden