"DIE Nothwendigkeit für zwei unvergleichbare Kreise von Erscheinungen zunächst zwei gesonderte Erklärungsgründe zu verlangen, verbot uns jeden Versuch, aus Wirkungen materieller Stoffe, so fern sie materiel sind, das innere Leben als einen selbstverstandlichen Erfolg ableiten zu wollen." - HERMANN LOTZE, Mikrokosmus, I., 186.

"ATTENTION to those philosophical questions which underlie all Science, is as rare as it is needful."- PROFESSOR T. H. HUXLEY, Contemporary Review, Nov., 1871, p. 443.

VII.

DOES DEATH END ALL?

INVOLUTION

AND EVOLUTION.

IF the Greeks had possessed the microscope, they would in all probability never have been thrown into debate over the famous question of their philosophy, whether the relation of the soul to the body is that of harmony to a harp, or of a rower to a boat (Plato, Phædon). According to the former of these two theories, the music must cease when the harp is broken: according to the latter, the rower may survive, although his boat is destroyed. He may be completely safe, even when his frail vessel, splintered by all the surges and lightnings, rots on the tusks of the reefs, or sinks in the fathomless waste, or dissolves to be blown about the world by the howling seas. In the one case, death does, in the other it does not, end all. Dim as was to the Greeks of Pericles' day the whole field which science has entered with the microscope for the first time in the last fifty years, all their greatest poets and philosophers held that the relation of the soul to the body is that of the rower to a boat. This was the common metaphor as men conversed on this theme under the Acropolis two

thousand years ago. Without Christian prejudices, Greek tragedy is full of the dying faith of Socrates. Eschylus, with his eyes of dew and lightning fixed on the fact of immortality, strikes the central chord of his harp; and one terrific thrum of it I often in still days hear across twenty centuries:

"Blood for blood, and blow for blow:

Thou shalt reap as thou didst sow."

What if Aristotle and Plato and Eschylus had had Beale's and Helmholtz's and Dana's eyes in the study of living tissues?

When modern investigation asserts that life directs the movements of bioplasm, it does not deny at all that currents of physical and chemical forces are floating around the bioplast boat. It asserts simply that the oars are in the hands of life. You will not

understand me to deny that the rower in the boat is aided by the currents beneath him, by the winds around him, and by his own weight and the inertia of his vessel. Nevertheless, between the rower and the boat on the one hand, and the inert log that may be floating beside him on the other, there is plainly all the difference that exists betwen the living and the not-living. Your rower takes advantage of all the forces around him; he can give them new directions; he presides over them. He can sail against the wind; he can row against the current; he governs the forces that wheel in mysterious complex cycles above and around and beneath him; he makes them his own, and so is a living thing on the water.

Just so, life uses the physical and chemical forces at work in living organisms.

There ought to stand before every discussion definitions, just as before one of Shakspeare's dramas there stand the names of the dramatis personæ. I know into what an intricate tropical forest of thought I am entering; and I am fully aware that the chief personage here is one whose character never has been successfully described in a definition. What is life? Thousands and thousands of definitions have been attempted of that term; and we have as yet in words no satisfactory statement of what life means; but we all understand very well what the thing is.

Herbert Spencer defines life as "The definite combination of heterogeneous changes, both simultaneous and successive, in correspondence with external co-existences and sequences." This definition has been very much admired; and I suppose you all understand what it means. The latest science finds this definition defective, because it does not limit the changes of which it speaks to one specifically constituted substance now known as bioplasm (DRYSDALE, Protoplasmic Theory of Life: London, 1874. P. 176).

I know what I venture; but, as my definition of life, I must give these words: The power which directs the movements of bioplasm. I beg you to notice that I do not say that life is the force which moves bioplasm, although, as a loose definition, the latter phrase would do. Bioplasm is moved in part by physical and chemical forces, though not chiefly. Chemical and physical forces, however, are not called living in the best

philosophy. To say that life is the force that moves bioplasm is to say that all the power there is in the river on which the boat and rower float originates in the rower. I say nothing of that sort. The force of the river belongs to the river; that of the oars, to the rower. The power which causes your skiff to move against the current, or which catches the wind in the sail, is that of its living occupant, who directs other forces, and puts forth force of his own. Nevertheless, in the motion of your little boat, there is a combination of the power of the rower and the power of the currents. So, in the motion of your bioplast, there is the agency of purely physical and chemical forces, together with the co-ordinating agency or directing power which weaves the tissues, and interweaves tissue with tissue into designs marvellous beyond comment, and which cannot be accounted for at all by any thing simply chemical or physical. I affirm, therefore, that life may be defined provisionally as the rower in the boat, or the power which directs the movements of germinal matter. To give a fuller definition, I may say that life is the invisible, individual, co-ordinating cause directing the forces involved in the production and activity of any organism possessing individuality. Of course the vitality of a cell differs from the life of the whole organism of which it forms a part; for many cells may die and the life of the organism to which they belong not be affected. Important distinctions exist between vitality, life, and soul. A single cell may have vitality; the individual organism to which the cell belongs