Page:On the characters, properties, and uses of Eucalyptus globulus and other species of Eucalyptus.djvu/11

 Having now described, as fully as time will allow, the general and botanical characters of the Eucalyptus globulus and other species of Eucalyptus, we proceed to refer to their properties and uses, with more especial reference to Eucalyptus globulus.

.—The first and most important influence which this tree exerts, and that which has brought it more especially into notice, is its power of destroying the malarious agency which is supposed to cause fever in marshy districts; from which circumstance it has been called "the fever-destroying tree."

It is in this respect commonly regarded as being serviceable in two ways—first, by the far-spreading roots of this gigantic tree acting like a sponge, as it were, and thus pumping up water and draining the ground; and, secondly, by emitting odorous antiseptic emanations from its leaves. Probably the influence of the latter is but small; although I am by no means of the opinion entertained by some writers, that these emanations are without effect. I do not certainly believe, as has been recently stated, that the branches of a solitary Eucalyptus tree can have had any effect in neutralizing the malarious influence of a district previously constantly infected by fever; but I do think that the foliage of groves of Eucalyptus trees, by diffusing an agreeable, aromatic, camphoraceous, stimulating odour in the surrounding air, does have an appreciable influence in neutralizing marshy miasmas, and thus improving the healthiness of the district. The great influence is, however, in my opinion, unquestionably produced by the power the roots possess of absorbing water from the soil. It is stated that a Eucalyptus tree absorbs as much as ten times its weight of water from the soil; and hence the enormous suction-power of masses of such trees may in some degree be judged of; so that, where thickly planted in marshy places, "the subsoil is drained in a little while as though by extensive piping."

That the main influence of Eucalyptus trees is thus due to the absorptive power of the roots is also borne out by the fact that other plants of rapid growth, when planted in marshy districts, have a sensible effect in diminishing their malarious influence. This is notably the case with the Sunflower, which is grown for this purpose to a large extent in the swampy regions of the Punjab and other parts of the world; and the effect has been that districts which were previously remarkable for their insalubrity are now said to be entirely free from miasmatic fever.

But whatever be the cause or causes which render a marshy district thus comparatively healthy to what it was before the intro-