LIFE, ANIMAL AND VEGETABLE. Ani mal and vegetable life has been defined, by Auguste Le Comte, as resulting from a double "molecular motion, general and continuous, of composition and decomposition, in relation to the organism and inorganic medium. This definition is correct enough asan hypothesis showing the action of life. What is life, is a question as .yet too profound for the mind of man to elucidate. The action of life upon the medium has been defined to be as supposing nbt only a being organized in such manner as to permit the phenomena constituting the vital state, but supposes further the not less indis pensable idea of the ensemble of external agents, physical and chemical, proper to furnish to the organism the principles necessary for its nutrition and 'the manifestation of the properties of its anatomical elements. This ensemble of condi tions we name the medium. The idea of life and that of the medium are two conceptions so inseparable from each other that no life is possible in a medium improper for the accom plishment of organic phenomena. There must be a certain harmony between these two media. As this harmony diminishes, the phenomenon passes from the normal state to that of sickness or perturbation, a prolongation of which occa sions death. Organic perturbation may occur in three different modes, which it is important to fully understand before proceeding to analyze the nature of the perturbation. Prof. Poey says: 1. If the medium is much more permanent, simpler, and more general, the living beiug alone is modified. 2. If the medium is much more unstable, more complex, and special, it is then more modifiable than the living being. 3. If the medium be as complex as the living being the modifications will correspond in both terms. In the capital question of the reciprocal influence of Climatologic agents upon living beings, and vice versa, the problem to be first resolved by way of experiment is the following: To learn and separ ate, in meteorological observations, the sum of the actions of the medium, gravity, heat, light, electricity, etc., favorable for organic existence, from the sum of actions unfavorable for this existence, and, after this correction, to calculate the effects of action and reaction between the being and the medium. This problem having been formulated by Alphonse de Candolle, solely with reference to the influence of temperature on vegetation, was extended by Prof. Poey to all the other meteorological influences, by introduc ing the most capital element of the action of media upon living beings, and of their reaction upon media—a consideration overlooked by this savant. The persistent harmony between vital forces and external modifiers, which concur in the phenomena of life, being thus established in the theory of media, the last problem remaining to be practically resolved is the following: A living being and a medium being given, to determine their reciprocal influence. Such was
the course pursued by Prof. Poey in examining those meteorologic and climatologic elements that exert any influence upon vegetable life, in its relation to the agricultural art. The principle of the correlation, conservation, and equivalency of heat and motion has been extended to all the forces both of organic and inorganic nature, and lately to the intellectual and moral functions. We thus identify all the forces acting in the living body with those acting in the inorganic universe, the former having only a higher degree , of complexity. Hence the organic constitution (animal and vegetable) may be compared to an engine in which heat is the principal agent. The power of the steam engine is derived from the heat applied to its boilers, which heat is but the expression of the chemical changes involved in combustion. The same with vegetable activity, ' the force of the solar light being used up in the decomposition of the carbonic acid of the atmos phere by the growing plant. Combustion in the furnace of the steam engine is sustained either by wood which is the product of vegeta tion or by coal which represents the vegetable life of a remote geological epoch. In either case, therefore, we come directly or indirectly to solar radiation. But as Liebig says, our animated machines create no power, but only return what they have received from the external medium. In fact. Liebig defined life to be that plants live and grow; while animals live, grow, and feel. This, while as a rule being correct, is not so, strictly speaking, since it is not possible to verify the statement as to the lowest forms of life any more certain than to state as a verity that vegeta bles do not feel. Some of the low forms of ani mal life seem to have no feeling, or indeed, power of voluntary motion. Some plants have the power of voluntary motion, as in the Sensi tive plant, which immediately folds its leaves upon being touched; others again, as some of the acacias, fold the leaves at night and seem to sleep. Again, an animal may consist of a sin gle cell, and in the lowest forms of life, there is neither muscular fiber, nervous filaments, head, heart, stomach, nor other organs common to most animals; they seem to live simply by absorption. Yet the absence of all these do not demonstrate that the substance is not animal. Albumen is the great nutritive element of animals, and starch of plants. So the chemical composition of the tissues of animals differs from that of plants. The basis of vegetable structure is cellu lose, (see Cellulose,) and yet in the lower pro tozoa, cellulose is found; just as in some low forms of vegetable life, (fungi,) starch is defi cient. Plants absorb and assimilate by their roots and leaves, and give off oxygen, retaining the carbon of carbonic acid, while animals digest their food, consume oxygen, and give off (respire) carbonic acid from the lungs. . (See articles Geheration and Germination.)