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CHAPTER II.

LIFE.

We know and can know nothing of life in the abstract-that is, apart from its manifestations; but that does not preclude us from endeavouring to discover its laws by the study of its phenomena, or the process of its evolution by tracing its progress in the races of plants and animals that successively appeared on the earth.

We know nothing in the abstract of the force called gravitation, but we conclude from its phenomena that there is a specific force that operates according to certain unvarying laws, and from these laws we can predicate how matter will be affected by gravitation under all known conditions.

Nothing is known of ether, and we have even no direct evidence of its existence, but scientific authorities assume that there must be a something which they name ether to

account for certain phenomena otherwise inexplicable.

Pursuing a similar line of inquiry, the phenomena of life presented during the growth of an organism from its germ-cell to maturity indicate that an organism is the product of three principal factors:The matter or food that goes to build up the organism;

The external conditions necessary for its growth; and

A combination of forces that actuates the general mechanism of the organism, selects and assimilates suitable food, and builds up a specific type.

Further, we may infer that the co-operating forces are of two kinds: a General force, common to all life; and a Specific force, peculiar to each race, that selects and assimilates suitable food, and builds up a specific type of that race.

It may be that the food assimilated reinforces the general life-force, but we cannot see how food or conditions of existence can provide the Specific life-force that forms the specific type.

We therefore infer that the Specific lifeforce of the organism comes from its germ-cell, and, as the germ-cell is the joint product of

the progenitors, that Specific life - force is transmitted by the progenitors and inherited by the progeny.

Now we know that the same physical force, acting under like conditions on the same kind of matter, is invariably attended by the same result, and if the same law extends to life-force, a Specific life-force, acting under like conditions in conjunction with the same kinds of matter, will invariably evolve an organism of the same type; and therefore, assuming that Specific lifeforce is transmitted from parent to offspring, heredity is a necessary outcome of reproduction like will produce like.

On the same principle, any difference in the potency of the General or of the Specific life-forces transmitted, or in the respective potencies of the two progenitors, will be attended by corresponding differences in the organism they produce.

It is common observation that individuals of the same race differ in inherited vitality or life-force, and we know that rarely do two individuals grow to maturity under the same conditions in respect of quality or quantity of food or external influences, and it therefore necessarily follows that there will be differences in what we call "expression of

type" arising from differences in the qualities inherited and in the conditions of development of the organism.

All individuals of the same type will not be identical like castings of the same metal from the same mould, but must vary from each other with any variation in the respective influences of the several factors to which they owe their existence and development.

On the preceding facts and observations we base the following working hypothesis, which we propose to use as a key to further discoveries, and to test by the explanation it offers of various phenomena of life.

Hypothesis.

Life is a combination of forces that, in conjunction with specific kinds of matter, evolves, under favourable conditions, and according to constant definite laws, animals and plants.

Every organism is evolved by a General life-force in combination with a Specific lifeforce.

The General life-force is common to all life, but the Specific life-force is peculiar to each race, and builds up its specific type.

The Specific life force determines the

type, but the expression of the type is the outcome partly of heredity and partly of the conditions of development.

The respective potencies, in modifying expression of type, of the General life-force, of the Specific life-force, and of the other factors of development, vary in different races and also among individuals of the same race or family.

Deductions.

From the preceding hypothesis come the following deductions :

Expression of type is affected by the quality or energy of the General and Specific life-forces, and by the conditions of develop

ment.

The development of a type cannot exceed a full expression of the energy of its life-forces.

Without modification of a Specific lifeforce there can be no specific variation in type.1

1 "Every variation of a living form, however minute, however apparently accidental, is inconceivable except as the expression of the operation of molecular forces or 'powers' resident within the organism. And as these forces certainly operate according to definite laws, their general result is, doubtless, in accordance with some general law which subsumes them all."-Huxley, Darwiniana, p. 182.

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