The young trees of course suffer by being stripped of their leaves, which are the _lungs_ of plants, and this is an additional reason for renewing them after a certain time. They endeavor in part to counteract the evil effect, by pruning and lopping the tree, so as to diminish the wood when the leaves have been gathered. It is surprising, however, to observe how soon a tree in those climates will recover its leaves in the summer or autumn, after having been entirely stripped of them by a typhoon or hurricane. Fresh plants are procured by cuttings or layers, and sometimes from seed. When the trees grow too old for the production of the finest leaves, and show a greater tendency to fruiting, they are either removed or so cut and managed as to produce young branches. The principal object, in the cultivation of the mulberry, is to produce the greatest quantity of young and healthy leaves without fruit. For this reason the trees are not allowed to exceed a certain age and height. They are planted on the plan of a quincunx[136], and said to be in perfection in about three years. [136] In _gardening_, the _quincunx_ order is a plantation of trees disposed in a square, consisting of five trees, one at each corner and a fifth in the centre, which order repeated indefinitely, forms a regular grove or wood, viewed by an angle of the square or parallelogram, presents equal or parallel alleys. Mr. Barrow, who observed the management of the trees and silk-worms in Chĕ-kiang, confirms the usual Chinese accounts, by saying that “the houses in which the worms are reared are placed generally in the centre of each plantation, in order that they may be removed as far as possible from every kind of noise; experience having taught them that a sudden shout, or the bark of a dog, is destructive of the young worms. A whole brood has sometimes perished from the effects of a thunder-storm.” Some notion of the extent of the care required in the management of the worms may be formed from the following extract, taken from the Chinese work referred to at the beginning of this chapter. “The place where their habitation is built must be retired, free from noise, smells, and disturbances of every kind. The least fright, makes great impressions on these sensitive creatures; even the barking of dogs, &c., is capable of throwing them into the utmost disorder.