differing, as we shall see, rather in degree than in kind as we descend the scale of living matter.

It is to be assumed that there is no risk of misconception in the use of such terms as living organism and life. The living organism is an entity which grows by absorption from outside, and which is capable of reproduction. It may have other functions; it always has in fact; but these two are essential. Its functions, separately considered, present to us the phenomena we call consciousness, and the sum of the functions, be they few or many, of an organism we call life. To state the case inversely: life is shown to us by acts of consciousness only, we have no other means of distinguishing between dead and living matter. Consciousness may further be described as effort to a definite end. We may not recognize the particular end in view, but if a purpose is obvious we must admit consciousness. We see a man making calculations on a piece of paper, though we do not know the problem he is working out; we have a heated discussion with a political or theological adversary, and we tell him, after a long speech, that we don't know what he is driving at; but none the less we admit these acts imply consciousness. The definition-effort to an end--is the basis of the present Essay. It may be insufficient, it may be incorrect, and it is certainly open to drastic criticism, it is, however, the best I am able to formulate, I cannot find another which will embrace such facts as have to be collated. And simple as the definition seems to be at first sight, it gives us quite enough to think about, the statement of the problem even on these lines is no easy matter, and, moreover, brings us no nearer to its solution. If it helps to make clear the relation of the various phenomena life presents to us, that is all we can ask of it, and it will have served its purpose well.

Let us begin, then, at the beginning. The earth in its solemn swing, the planets in their never hastening, never tiring procession-do they give us any sign of consciousness? None that we have yet recognised. Their motion is apparently impressed upon them by the one great force which binds other solar systems together, and which controls them no more and no less than it does the smallest grain of sand upon our sea shores. Regarded as one body, each planet seems under the complete dominion of the force of gravitation—subject to it as we see by its axial and orbital revolutions, exercising it as we see by its inducing like revolutions in its satellites. No purpose is evident to us. In fact the very regularity of these motions would of itself forbid our thinking of them as conscious. Regular invariable motion of any kind seems opposed to consciousness; irregular variable motion seems to imply it. When we come, however, to regard the matter of which our planet is composed, a very different series of phenomena presents itself. A careful examination reveals to us some 68 substances, which, with the means now at our disposal, we cannot reduce; they are called, therefore, elementary substances, and it is they and their combinations which account for all matter on the earth. These elementary substances exist in widely different conditions, someoxygen and hydrogen, for instance-are gases at ordinary temperatures; mercury and bromine are liquid; the greater number are solid. Some, like gold, are found native pure, but in most cases they exist in nature only in combination, and can be isolated only with great difficulty. Their combinations are found to be regular and in definite invariable proportions, following a law which has been formulated by comparisons of their relative weights. Thus, taking the lightest of the elementary substances, Hydrogen, as 1, we find oxygen always combining as 15·96, or a

simple multiple of that number. This, moreover, represents the weight of oxygen, bulk for bulk, under equal conditions as compared with Hydrogen-that is, if a globe filled with hydrogen weighs 1 lb. net, the same globe filled with oxygen, under exactly the same conditions of temperature, pressure, etc., would weigh 15.96 lbs. net, and if filled with mercury would weigh 199.8 lbs.

These figures: H= 1,

0 = 16,

Mercury=200, gives us the invariable proportions of H, O, and Hg. in their respective compounds. Take a simple example: Water, H, O, is a compound of two parts of H and one of O. (We eliminate fractions for the sake of brevity).

2

so that in 18 ozs. or 18 lbs. or 18 tons of water there will be 16 ozs. or 16 lbs. or 16 tons of oxygen, and 2 ozs. or 2 lbs. or 2 tons of hydrogen, and this of course can be proved empirically. These facts, and some others arising out of them are embodied in the atomic theory. Matter in its original form is supposed to exist in grains or atoms all of the same size, so that if we could get an atom of oxygen it would weigh 16 times the atom of hydrogen, and the mercury atom would weigh nearly 200 times the hydrogen atom. These atoms represent the smallest quantity of the substance that can exist even in combination, and it is suggested that if by any means we could divide an atom of silver, for instance, the resulting parts would not be silver at all, but that primary form of matter from which silver and all the elementary substances are derived. This, of course, is a supposition, but it is one to the truth of which

facts point. Now, in connection with the combination of these atoms some significant facts are to be noted: Mix H and O in a glass bottle-both are colourless gases, and you have a colourless transparent mixture; the gases are only mixed, they have not combined. Expose the bottle to the sun; an explosion takes place, and the gases have combined to form water. If there was a wrong proportion of H or O in the bottle-that is, if there were not exactly two parts by volume of hydrogen to each part of oxygen, the surplus quantity would remain uncombined. Continue the experiment: take the water produced by the explosion, place in it another elementary substance, sodium, the water is again decomposed, one atom of the sodium combining with one atom of the O and one atom of the H to form caustic soda, the remaining

atom of H being set free.

The atomic weight of sodium as compared with H is 23, so that if we had 23 lbs. of Sodium and 18 lbs. of water, we should have exactly

Na 23

H 1

O 16

40 lbs. of Na HO

and 1 lb. of H.

And if we put 24 lbs. of sodium into 18 lbs. of water, 1 lb. of H. would still be set free, and 1 lb. of sodium would remain uncombined. If we had put gold or platinum in the water instead of sodium, no change would have taken place, these metals not having the power to decompose water as sodium does. There is no need to cite further examples, every text-book of chemistry will furnish them, and we have only to indicate the unexplained force of chemical affinity. How is it that every atom of O in a

mixture of H and O combines with two atoms of H and no more, to form water? How is it that in no circumstances can we get an atom O to combine with more than two atoms of H? (If an atom of O cannot get two atoms of H, it will combine with one, but the combination is highly unstable, the O is always on the look out, so to speak, for the other atom of H, and seizes the first that comes in its way). How is it that the atom of sodium can displace an atom of H in water, forming caustic soda, while neither gold nor platinum can do so. I do not know. No one knows. But it is here, I submit, somewhere here among these elements of our earth's crust, that we must look for the solution of the problem of consciousness. And let us beware at this point of an almost inveterate tendency to dismiss such questions as these by postulating an anterior force of any kind. It is easy to say-one section of the community is constantly saying it—yes, these atoms display certain powers, certain qualities, but their powers and qualities were given to them, impressed upon them by another power outside and beyond them. The matter cannot be in this way settled. The difficulty has only been put a step further back, and in putting it back we don't overcome it, we increase it immensely, since, if an outside unknown power has impressed these elementary substances with their known functions, this outside power must continually operate, it must always have operated, there can be no limit to it. Our minds refuse, however, to conceive of such a power as this. Such as our experience is, it is finite, it has reference only to existences of which it is cognizant, and of which the beginning and end can be conceived. Power, apart from an existence is inconceivable. We may use phrases or terms which, by repetition, have become familiar, but on examination they answer to no mental conception. If we cannot conceive of