CHAPTER IV.
EVOLUTION AND MUTABILITY OF LIVING MATTER AND BRUTE MATTER.
Supposed immobility of brute bodies—Mobility and mutability of the sidereal world.—§ 1. The movement of particles and molecules in brute bodies—The internal movements of brute bodies—Kinetic conception of molecular motion—Reality of the motion of particles—Comparison of the activity of particles with vital activity.—§ 2. Brownian movement—Its existence—Its character—Its independence of the nature of the bodies and of the nature of the environment—Its indefinite duration—Its independence of external conditions—The Brownian movement must be the first stage of molecular motion.—§ 3. Motion of particles—Migration of material particles—Migration under the action of weight; of diffusion; of electrolysis; of mechanical pressure.—§ 4. Internal activity of alloys—Their structure—Changes produced by deforming agencies—Slow return to equilibrium—Residual effect—Effect of annealing; effect of stretching—Nickel steel—Colour photography—Conclusion—Relations of the environment to the living or brute matter.
One of the most remarkable characteristics of a living being is its evolution. It undergoes a continuous change. It starts from something very small; it assumes a configuration and grows; in most cases it declines and disappears, having followed a course which may be predicted—a sort of ideal trajectory.
Supposed Immobility of Brute Bodies.—It may be asked whether this evolution, this directed mobility, is so exclusively a feature of the living being as it appears, and if many brute bodies do not present something analogous to it. We may answer in no uncertain tones.
Bichat was wrong when he contrasted in this respect brute bodies with living bodies. Vital properties, he said, are temporary; it is their nature to be exhausted; in time they are used up in the same body. Physical properties, on the contrary, are eternal. Brute bodies have neither a beginning nor an inevitable end, neither age, nor evolution; they remain as immutable as death, of which they are the image.
Mobility and Mutability of the Sidereal World.—This is not true, in the first place, of the sidereal bodies. The ancients held the sidereal world to be immutable and incorruptible. The doctrine of the incorruptibility of the heavens prevailed up to the seventeenth century. The observers who at that epoch directed towards the heavens the first telescope, which Galileo had just invented, were struck with astonishment at discovering a change in that celestial firmament which they had hitherto believed incorruptible, and at perceiving a new star that appeared in the constellation Ophiuchus. Such changes no longer surprise us. The cosmogonic system of Laplace has become familiar to all cultivated minds, and every one is accustomed to the idea of the continual mobility and evolution of the celestial world. “The stars have not always existed,” writes M. Faye; “they have had a period of formation; they will likewise have a period of decline, followed by final extinction.”
Thus all the bodies of inanimate nature are not eternal and immutable; the celestial bodies are eminently susceptible of evolution, slow indeed with that we observe on the surface of our globe; but this disproportion, corresponding to the immensity of time and of cosmic spaces as compared with terrestrial measurements, should not mislead us as to the fundamental analogy of the phenomena.
§ 1. The Movement of Particles and Molecules in Brute Bodies.
It is not only in celestial spaces that we must search for that mobility of brute matter which imitates the mobility of living matter. In order to find it we have only to look about us, or to inquire from physicists and chemists.
As far as geologists are concerned, M. le Dantec tells us somewhere of one who divided minerals into living rocks—rocks capable of change of structure, of evolution under the influence of atmospheric causes; and dead rocks—rocks which, like clay, have found at the end of all their changes a final state of repose. Jerome Cardan, a celebrated scientist of the sixteenth century, at once mathematician, naturalist, and physician, declared not only that stones live, but that they suffer from disease, grow old, and die. The jewellers of the present day use similar language of certain precious stones; the torquoise, for example.