" Animals, as we all know, are liable to a great variety of diseases ; so, too, are vegetables ; to diseases as numerous, as varied, and as fatal; to diseases epi demic, endemic, sporadic ; to scabies, pernio ulcer, gangrene; to polysarca, atrophy, and, above all, to invermination. Whatever, in fine, be the system of noso logy to which we are attached, it is im possible for us to put our hand upon any one class or order of diseases which they describe, without putting our hand, at the same time, upon some disease to which plants are subject in common with animals.
" There are some tribes of animals that exfoliate their cuticle annually; such are grass hoppers, spiders, several species of crabs, and serpents. Among vegetables we meet with a similar variation from the common rule, in the shrubby cinque foil, indigenous to Yorkshire, and the plane-tree of the West Indies. Animals are occasionally divided into the two classes of locomotive or migratory, and fixed or permanent; vegetables may par take of a similar classification. Unques tionably the greater number of animals are of the former section, yet in every or der of worms we meet with some instan ces that naturally appertain to the latter, while almost every genus and species of the zoophytes can only be included under it. Plants, on the contrary, are for the most part stationary, yet there are many that are fairly entitled to be regarded as locomotive or migratory. The strawberry may be selected as a familiar example." Plants, like animals, have a wonderful power of maintaining their common tem perature, whatever be the temperature of the atmosphere that surrounds them, and like animals, they are found to exist in astonishing degrees of heat and cold. Of these, Mr. Good has given many curious instances. Animals are'ofien divided into the three classes of terrestrial, aquatic, and aerial. Plants are capable of a simi lar division. Among animals, it is pro bable that the largest number is of the first class, but among vegetables, it should seem, from the almost countless species of fuel, &c. that the largest number be longs to the submarine class Many ani mals are amphibious, or capable of pre serving life in either element ; the vege table world is not without instances of a similar power. Animals of various kinds are aerial : all the most succulent plants of hot climates are of this description : these will only grow in soils or sands from which no moisture can be extracted : they are even destroyed by a full supply of wet by a rainy season : hence it has been sup posed, that they derive the whole of their nourishment from the surrounding atmos phere, and that the only advantage which they acquire from thrusting their roots into such strata, is that of obtaining an erect position. Some quadrupeds seem
to derive nutriment in the same manner. The bradypus, or sloth, never drinks, and trembles at the feeling of rain. Among plants, possessing the same properties, is the aerial epidendrum, a native of the East Indies, where it is no uncommon thing for the inhabitants to pluck it up, on account of the elegance of its leaves, the beauty of its flower, and the exquisite odour it diffuses, and to suspend it by a silken cord from the ceiling of their rooms, where, from year to year, it continues to put forth new leaves, new blossoms, a new fragrance, excited alone to new life and action by the stimulus of the sur rounding atmosphere. " That stimulus is oxygen ; ammonia is a good stimulus, butoxygen possesses far superior powers, and hence, without some portion of oxy. gen, no plant can ever be made to germi nate : hence, to the use of cow•dung, and other animal recrements, which consists of muriatic acid and ammonia, while in fat oil and other fluids, that contain little or no oxygen, and consist altogether, or nearly so, of hydrogen and carbon, seeds may be confined for ages without exhibit ing any germination whatever. And hence, again, and the fact deserves to be extensively known, however torpid a seed may be, and destitute of all power to ve getate in any other substance, if steeped in a diluted solution of oxygenated muri atic acid, at a temperature of about 46° or 48° of Fahrenheit, provided it still pos sess its principle of vitality, it will ger minate in a few hours ; and if, after this, it be planted, as it ought to be, in its ap propriate soil, will grow with as much speed and vigour as if it had evinced no torpidity whatever." The author next proceeds to enquire into the mode by which vegetable matter is capable of being converted into animal substance, so as not only to be perfectly assimilated to it, but to become the basis of animal nutriment and increase. "Now, to be able to reply succinctly and direct ly to this question, it is necessary first of all to inquire into the chief feature in which animal and vegetable substances agree, and the chief feature in which they disagree.