USES OF LEAVES. 141 



culiar fragrance of the plant which exhales it. When 

 the temperature suddenly changes, the insensible per- 

 spiration is sometimes condensed, in the form of tears. 

 This was observed by the Roman Poet, whose my- 

 thology had transformed the mournful sisters of Phae- 

 ton into Poplars, and the fluids which glittered on their 

 leaves, were the tears which bespoke their anguish. 



It may frequently be observed on the leaves of those 

 plants, which delight in moist shady situations, and fade 

 rapidly whenever they are removed. The Lnpatiens 

 fulva, termed on account of its elastic capsules Touch- 

 me-not, is one of this kind. I have frequently seen it 

 when every other plant around was dry ; yet its leaves 

 glittered with the vapour, which in the form of tears, 

 had been condensed on their surface. 



Very different from condensed vapour, are the exu- 

 dations, which frequently appear on the leaves of dif- 

 ferent plants ; and which are either an effusion of heal- 

 thy secretion, or an indication of disease. The Honey- 

 dew, which is seen on the leaves of the Beech, is oc- 

 casioned by dampness of the atmosphere, and denotes 

 its unhealthy condition ; but Manna frequently covers 

 the leaves of the healthy Ash, from which tree it is 

 usually obtained, as we procure sugar from the Maple. 

 Sometimes this effusion possesses adhesive properties, 

 sometimes it is intensely bitter, and in some cases highly 

 inflammable. 



Leaves are organs of Absorption. The use of a tin 

 box to preserve their freshness has already been noticed. 

 If it contains a minute quantity of water, it will restore 

 to the vigour of health, the fading and the dying leaf. 

 This renovation arises from its power to imbibe mois- 

 ture from the atmosphere of the box in which it is con- 

 fined ; a power which most leaves possess, though in 



