We see matter all about us, acted upon by the mechanico-chemical forces, that never takes on any of the distinctive phenomena of living bodies.  Yet Verworn is convinced that if we could bring the elements of a living body together as Nature does, in the same order and proportion, and combine them in the selfsame way, or bring about the vital conditions, a living being would result.  Undoubtedly.  It amounts to saying that if we had Nature’s power we could do what she does. If we could marry the elements as she does, and bless the banns as she seems to, we could build a man out of a clay-bank.  But clearly physics and chemistry alone, as we know and practice them, are not equal to the task.

III

One of the fundamental characteristics of life is power of adaptation; it will adapt itself to almost any condition; it is willing and accommodating.  It is like a stream that can be turned into various channels; the gall insects turn it into channels to suit their ends when they sting the leaf of a tree or the stalk of a plant, and deposit an egg in the wound.  “Build me a home and a nursery for my young,” says the insect.  “With all my heart,” says the leaf, and forthwith forgets its function as a leaf, and proceeds to build up a structure, often of great delicacy and complexity, to house and cradle its enemy.  The current of life flows on blindly and takes any form imposed upon it.  But in the case of the vegetable galls it takes life to control life.  Man cannot produce these galls by artificial means.  But we can take various mechanical and chemical liberties with embryonic animal life in its lower sea-forms.  Professor Loeb has fertilized the eggs of sea-urchins by artificial means.  The eggs of certain forms may be made to produce twins by altering the constitution of the sea-water, and the twins can be made to grow together so as to produce monstrosities by another chemical change in the sea-water.  The eyes of certain fish embryos may be fused into a single cyclopean eye by adding magnesium chloride to the water in which they live.  Loeb says, “It is a priori obvious that an unlimited number of pathological variations might be produced by a variation in the concentration and constitution of the sea water, and experience confirms this statement.”  It has been found that when frog’s eggs are turned upside down and compressed between two glass plates for a number of hours, some of the eggs give rise to twins.  Professor Morgan found that if he destroyed half of a frog’s egg after the first segmentation, the remaining half gave rise to half an embryo, but that if he put the half-egg upside down, and compressed it between two glass plates, he got a perfect embryo frog of half the normal size.  Such things show how plastic and adaptive life is.  Dr. Carrel’s experiments with living animal tissue immersed in a proper mother-liquid illustrate how the vital process—­cell-multiplication—­may