300 THE NURSERY. [MARCH 



In Sicily, the three species above mentioned, with the view of ob- 

 taining manna from them, but more particularly the first, are planted 

 on the declivities of hills, having eastern aspects. After ten years' 

 growth the trees first begin to yield manna, but they require to be 

 much older before they afford it in any considerable quantity. Al- 

 though the manna exudes spontaneously from the trunks and 

 branches, yet in order to obtain it more copiously, incisions are made 

 through the bark, by means of a sharp crooked instrument, a slice 

 of which is taken off, about three inches in length and two in breadth; 

 they leave the wounds open, and by degrees the manna runs out. 

 The season thought to be most favorable for instituting this process, 

 is a little before the dog-days commence, when the weather is dry 

 and serene. The incisions are first made in the lower part of the 

 trunk, and repeated at the distance of an inch or two from the for- 

 mer wound, still extending them upwards as far as the branches, and 

 confining them to one side of the tree, the other side being reserved 

 till the year following, when it undergoes the same treatment. On 

 making these, a thick white juice immediately begins to flow, which 

 gradually hardens on the bark, and in the course of eight days ac- 

 quires the consistence and appearance in which the manna is imported, 

 when it is collected in baskets and afterwards packed in large chests. 

 Sometimes the manna flows in such abundance from the incisions, 

 that it runs upon the ground, by which it becomes mixed with vari- 

 ous impurities, unless prevented, which is commonly attempted by 

 interposing large concave leaves, stones, chips of wood, &c. The 

 business of collecting it, generally terminates in those countries in 

 September, when the rainy season sets in. 



That manna is got in quantities on the leaves of trees, is an 

 opinion taken from the doctrine of the ancients, and received as in- 

 contestible without consulting nature ; for all those who are employed 

 in the gathering of it, know of none that comes from the leaves ; 

 therefore, that with which the Israelites were so peculiarly favored, 

 could only have been produced through miraculous means, and is 

 consequently out of the province of the naturalist. The best manna 

 is what exudes from the tree very slowly, and is collected clean ; this 

 is always more dry, transparent, and pure, for when it flows copiously 

 it concretes into a coarse, brown, unctuous mass. 



METHODS OF PROPAGATING TREES AND SHRUBS BY LAYERS. 



There are few trees or shrubs, if any, but may be increased in 

 this way. The nursery gardeners who want to propagate large quan- 

 tities of various hardy kinds, of which they cannot easily procure 

 seeds, and which by experience they do not find to grow freely by 

 cuttings, establish what they call stools, of the different kinds in- 

 tended to be propagated, particularly of the deciduous tribe, and also 

 some evergreens. For this purpose they plant in different quarters, 

 stout, healthy plants, at the distance of four or five feet from one 

 another every way, and head them down; these throw out near the 

 earth a number of young shoots, some of which may be laid in the 

 autumn or spring following; these stools, as they are commonly 



