VIII

ON THE PHYSICAL BASIS OF LIFE

SO

In order to make the title of this discourse generally intelligible, I have translated the term "Protoplasm," which is the scientific name of the substance of which I am about to speak, by the words 5"the physical basis of life." I suppose that, to many, the idea that there is such a thing as a physical basis, or matter, of life may be novel widely spread is the conception of life as a something which works through matter, but is independent of Io it; and even those who are aware that matter and life are inseparably connected, may not be prepared for the conclusion plainly suggested by the phrase, "the physical basis or matter of life," that there is some one kind of matter which is common to all 15 living beings, and that their endless diversities are bound together by a physical, as well as an ideal,

unity. In fact, when first apprehended, such a doctrine as this appears almost shocking to common

sense.

What, truly, can seem to be more obviously different from one another, in faculty, in form, and in 5 substance, than the various kinds of living beings? What community of faculty can there be between. the brightly coloured lichen, which so nearly resembles a mere mineral incrustation of the bare rock on which it grows, and the painter, to whom 10 it is instinct with beauty, or the botanist, whom it feeds with knowledge?

Again, think of the microscopic fungus - a mere infinitesimal ovoid particle, which finds space and duration enough to multiply into countless millions 15 in the body of a living fly; and then of the wealth of foliage, the luxuriance of flower and fruit, which lies between this bald sketch of a plant and the giant pine of California, towering to the dimensions of a cathedral spire, or the Indian fig, which covers 20 acres with its profound shadow, and endures while nations and empires come and go around its vast circumference. Or, turning to the other half of the world of life, picture to yourselves the great Finner

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whale, hugest of beasts that live, or have lived, disporting his eighty or ninety feet of bone, muscle, and blubber, with easy roll, among waves in which the stoutest ship that ever left dockyard would 5 founder hopelessly; and contrast him with the invisible animalcules mere gelatinous specks, multitudes of which could, in fact, dance upon the point of a needle with the same ease as the angels of the Schoolmen could, in imagination. With these images before your minds, you may well ask, What community of form, or structure, is there between the animalcule and the whale; or between the fungus and the fig-tree? And, a fortiori, between all four?

Finally, we. regard substance, or material com15 position, what hidden bond can connect the flower which a girl wears in her hair and the blood which courses through her youthful veins; or, what is there in common between the dense and resisting mass of the oak, or the strong fabric of the tortoise, and 20 those broad disks of glassy jelly which may be seen.

pulsating through the waters of a calm sea, but which drain away to mere films in the hand which raises them out of their element?

Such objections as these must, I think, arise in the

mind of every one who ponders, for the first time, upon the conception of a single physical basis of life underlying all the diversities of vital existence; but I propose to demonstrate to you that, notwithstanding these apparent difficulties, a threefold unity 5 —namely, a unity of power or faculty, a unity of form, and a unity of substantial composition — does pervade the whole living world.

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No very abstruse argumentation is needed, in the first place, to prove that the powers, or faculties, 10 of all kinds of living matter, diverse as they may be in degree, are substantially similar in kind.

Goethe has condensed a survey of all the powers

of mankind into the well-known epigram:

"Warum treibt sich das Volk so und schreit? Es will sich 15 ernähren,

Kinder zeugen, und die nähren so gut es vermag.

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Weiter bringt es kein Mensch, stell' er sich wie er auch

will."

In physiological language this means that all the 20 multifarious and complicated activities of man are comprehensible under three categories. Either they

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are immediately directed towards the maintenance and development of the body, or they effect transitory changes in the relative positions of parts of the body, or they tend towards the continuance of the 5 species. Even those manifestations of intellect, of feeling, and of will, which we rightly name the higher faculties, are not excluded from this classification, inasmuch as to every one but the subject of them, they are known only as transitory changes in the relative positions of parts of the body. Speech, gesture, and every other form of human action are, in the long run, resolvable into muscular contraction, and muscular contraction is but a transitory change in the relative positions of the parts of a muscle. 15 But the scheme which is large enough to embrace the activities of the highest form of life, covers all those of the lower creatures. The lowest plant, or animalcule, feeds, grows, and reproduces its kind. In addition, all animals manifest those transitory 20 changes of form which we class under irritability and contractility; and, it is more than probable, that when the vegetable world is thoroughly explored, we shall find all plants in possession of the same powers, at one time or other of their existence.