LE.V 



LEA 



ble, and furnish the principal means 

 of recognising species of phints ; they 

 are also occasionally covered with 

 hairs, glands, prickles, and, for the 

 most part, with minute openings on 

 the under surface, called slomata. 



Physiologically, the leaf is not only 

 the most im[)ortant portion of a plant, 

 but the only living portion ; the trunk 

 and roots are only fibres extended 

 from the leaves : the fruit and seed 

 are only modified leaves ; they pro- 

 duce the buds of plants, the great 

 means of propagation ; hence, in the 

 vegetable kingdom, more than half of 

 the known plants are no more than a 

 leaf, or foliaceous organ, as in ferns, 

 lichens, sea-weeds, fungi, and moss- 

 es ; and the leaf alone of many 

 plants is capable of giving rise to a 

 new individual, forming a root, a new 

 bud, and uUimately the entire tree or 

 plant ; thus, the orange, water-cress, 

 mint, hoya, clinanthus, and other spe- 

 cies, have been propagated by a leaf. 

 The planted leaf swells at its stalk, ' 

 emits roots, and develops a bud. i 



A leaf is a porous or spongy body ; 

 the gases and fluids of the interior of 

 the plant, and the gases and fluids of 

 the air mingle together by chemical 

 laws in its structure ; light, acting 

 on these, produces a change of com- 

 position, and establishes a move- 

 ment. Out of carbonic acid gas and 

 water, light, and the chemical actions 

 of the leaf, evolve sugar, gum, starch, 

 and wood ; these principles, acted 

 upon by other substances present, 

 produce, in part, albumen, fibrin, oils, 

 &c. ; and thus, primarily in the leaf, 

 all the products of vegetation are 

 formed, and hence they become dis- 

 tributed throughout the whole plant. 



The leaf only, with the green parts, 

 can elaborate sap for the whole ve- 

 getable ; the apparent changes in the 

 ascending sap are an increased den- 

 sity, and the separation of oxygen 

 and nitrogen gases, which escape into 

 the air. Leaves are to be carefully 

 preserved as the elaborating organs 

 of the plant, out of which come 

 growth and vigour. 



L E A F B U D. The collection of 

 small leaves with a central point 



capable of expansion, which is pro- 

 duced at the base or axil of the 

 leaves. In the bark is laid up a de- 

 posite of food for their use in spring, 

 upon which the bud, whether separa- 

 ted to another tree (m budding), or 

 remaining in its native place, feeds 

 while young ; by its expansion, a 

 shoot is formed. Leaf buds perpet- 

 uate all the peculiarities of the tree 

 on which they originated. 



LE.\FLET. The lesser leaves of 

 a compound leaf. 



LEAF MANURE. The dead leaves 

 of the forest constitute an admirable 

 manure when rotted in the farm-yard, 

 pig-stalls, or in composts ; they have 

 precisely the value of straw, being 

 very similar in their action. The 

 leaves of oaks and plants growing on 

 a rich soil are better than those of 

 pine, or such as grow on poor lands. 

 They should be collected as early as 

 possible in the fall. If ploughed into 

 the soil directly, they form an excel- 

 lent amendment, but require rather 

 more time to yield vegetable food. 

 In this case, lime should be applied 

 with the leaves. 



LEAF STALK. The petiole. 

 Leaves destitute of stalk are called 

 sessile. 



LEAGUE. The sea league is the 

 one tvi-entieth of a degree, or 345 

 miles. The French posting league is 

 2-42 English miles. 



LEAN-TO. A building whose raf- 

 ters lean or pitch against the wall of 

 another building. 



LEASH. A line to couple dogs. 

 Three head of game. 



LEATHER. Skins of animals 

 preserved by rendering their gelatin 

 insoluble and impermeable to water ; 

 this is called tanning, when a solution 

 of tannin is used, and the product 

 becomes tannogclaim. 



Taiccd leather is formed by steep- 

 ing prepared skins in potash liquor 

 and a solution of common salt and 

 alum ; in this way the resulting salt 

 of alumina combines with the gela- 

 tin : glove leather is so formed. 

 Curried leather is smeared with oil 

 while moist, which gradually pene- 

 trates the skin as it dries. A perfect 



4.53 



