incoherent movements of numberless hosts of matter, each of which goes its own way and all of which hold each other in equilibrium.
If it were only astronomy that were undergoing this change! But no; the same modification takes place in the philosophy of all sciences without exception; those which study nature as well as those which study human relations.
In physical sciences, the entities of heat, magnetism, and electricity disappear. When a physicist speaks to-day of a heated or electrified body, he no longer sees an inanimate mass, to which an unknown force should be added. He strives to recognize in this body and in the surrounding space, the course, the vibrations of infinitely small atoms which dash in all directions, vibrate, move, live, and by their vibrations, their shocks, their life, produce the phenomena of heat, light, magnetism or electricity.
In sciences that treat of organic life, the notion of species and its variations is being substituted by a notion of the variations of the individual. The botanist and zoologist study the individual—is life, his adaptations to his surroundings. Changes produced in him by the action of drought or damp, heat or cold, abundance or poverty of nourishment, of his more or less sensitiveness to the action of exterior surroundings will originate species; and the variations of species are now for the biologist but resultants—a given sum of variations that have been produced in each individual separately. A species will be what the individuals are, each undergoing numberless influences from the surroundings in which they live, and to which they correspond each in his own way.
And when a physiologist speaks now of the life of a plant or of an animal, he sees rather an agglomeration, a colony of millions of separate individuals than a personality one and indivisible. He speaks of a federation of digestive, sensual, nervous organs, all very intimately connected with one another, each feeling the consequence of the well-being or indisposition of each, but each living its own life. Each organ, each part of an organ in its turn is composed of independent cellules which associate to struggle against conditions unfavorable to their existence. The individual is quite a world of federations, a whole universe in himself.
And in this world of aggregated beings the physiologist sees the autonomous cells of blood, of the tissues, of the nerve-centres; he recognizes the millions of white corpuscles—the phagocytes—who wend their way to the parts of the body infected by microbes in order to give battle to the invaders. More than that: in each microscopic cell he discovers to-day a world of autonomous organisms, each of which
