318 The Death and Fall of Leaves. 



moved from the ground ; and these labels are generally of zinc 

 attached by wire. 



Dahlias are propagated either by dividing the fascicles of 

 tubers, by cuttings, or by seeds. By the first mode, the roots 

 are planted either in the ground, or in pots plunged in a hot- 

 bed, until they are started — that is, till the}' begin to grow 

 they are then taken up, and the tubers cut or pulled asunder 

 taking care that there is a bud or eye to each. Those which 

 have no buds are termed blind tubers, and they may have 

 buds inserted from other plants, by either cleft or peg grafting 

 The cuttings are either slipped off from started tubers with a 

 portion of the tuber attached, or made like cuttings of other 

 plants, by taking off part of a shoot in summer. In both cases 

 they require what is called bottom heat, that is, plunging the 

 pot into a hot-bed, to make them strike. Summer cuttings are 

 rarely made, unless it be of some new or choice sort, as the 

 stems are too succulent to strike easily. The seeds should be 

 sown on a slight hot-bed in February or March, or in a warm 

 border in the open garden. The seedlings must be transplanted 

 into beds, as soon as they have four or six leaves, or they will 

 be drawn up and become weak. 



THE DEATH AND FALL OF LEAVES. 



BT OR. GRAY. 



Leaves usually exist but for a single year. Most ever- 

 greens are scarcely exceptions, as their old leaves commonly 

 fall, or at least become inactive, soon after those of the ensuing 

 season are developed. Yet in some cases (as in Firs, &c.) they 

 do survive for a series of years. On the other hand, it is sel- 

 dom that all the leaves of an herb endure through the whole 

 growing season ; but the earlier foliage near the base of 

 the stem perishes and falls, while fresh leaves are still appear- 

 ing at the summit. In our deciduous trees and shrubs, how- 



