and this implied that what is called "suspended animation" was not really a possible thing, but that there could only be an apparent or approximate suspension. On the contrary, it seems that just as we may stop a watch by holding back the balance-wheel with a needle, and yet not "kill" the watch-for it will resume its movement as soon as the needle is removed so the changes of the chemical molecules of protoplasm can be arrested, but if the chemical" structure" is uninjured the mechanism of protoplasm can resume its activity when the arresting causes are removed. The inactive, unchanging protoplasm is not "dead," it has not been "killed" so long as its mechanism is intact.

On the other hand, it is the fact that this mechanism -the chemical structure of protoplasm-is very easily destroyed. A unicellular organism is chemically destroyed by crushing or disruption, and the consequent admixture of an excess of water with its particles, also by a temperature high enough to cause pain if applied to our skin, but yet much below that of boiling water, also by strong sun-light, and by very many varieties of chemical substances, especially acids, even when very much diluted. Complex animals and plants are liable to have the protoplasm of essential and important cells of the body destroyed, whereupon the destruction or death of the other cells, not involved in the original trouble, frequently and as a rule results. The protoplasm of the cells of a complex animal is dependent on the proper activity of many other cells besides those of its own tissue or locality in the body. If the protoplasm of certain nerve-cells or of blood-cells or of digestive-cells is poisoned or injured or chemically upset, other cells lose as a consequencenot at once but after a short interval-their necessary chemical food, their oxygen, their accustomed temperature, and so bit by bit the great "body"—the complex

organism-ceases to live, that is to say, its protoplasm undergoes step by step and bit by bit irrevocable chemical change or breaking down.

When a man enters upon that condition which we call "death," the general muscular movements first cease, then the movements of respiration (so that a mirror held to the mouth was used to test the coming and going of the breath, and the absence of a film of moisture on the mirror's surface was held to be a proof of death), then the movement of the heart, which is followed by the awful pallor of the bloodless face and lips, and the chilling of the whole body, no longer warmed by the blood-stream. But for long after these changes have occurred the protoplasm of the cells in many parts is not injured. The beard of a corpse will grow after all the great arrests of movement above noted have been established for hours. In cold-blooded animals, such as the frog, the protoplasm of the muscles is still uninjured many hours after decapitation, and they can be stimulated and made to contract. Death, in fact, only occurs in the tissues of a multicellular animal, as their protoplasm becomes chemically destroyed by injurious temperature, poisonous accumulations, or active bacterial germs, which become predominant owing to the stoppage of the great mechanisms of breathing, circulation, and nerve control.

Is it, then, necessary to suppose that a something, an essence, a spirit, an intangible existence called "life" or "vitality," or the "anima animans," passes away, or, as it were, evaporates from a thing which was living and is now dead? Assuredly no more than it is necessary to suppose that an essence or thing called "death" takes possession of it when it ceases to carry on the changes which we call "living." It must not be supposed that we regard the unique and truly awe-inspiring processes

for,

which go on in the protoplasm of living things as something simple, easily understood and accounted because we have given up the notion that life is an entity which enters into living things from without and escapes from them at death. The real fact is, that the notion of "spirits," whether of a lower or of a higher kind, supposed to enter into and "affect" various natural objects, including trees, rivers, and mountains, as well as animals and man, does not help us, and only stands in the way of our gaining more complete knowledge of natural processes. When we say that life and even its most tremendous outcome—the mind of man-are to be studied and their gradual development traced as part of the orderly unfolding of natural processes, we are no whit less reverent, in no degree less impressed by the wonder, immensity, and mystery of the universe, than those who, with happy and obstinate adherence to primitive conceptions, think that they can explain things by calling up vital essences and wandering spirits.

WH

XX

CHEMISTRY AND PROTOPLASM

HEN the chemist examines living cell-substance or protoplasm-as free as possible from dead envelopes and products of its own activity—so as to make out, if he can, what it is chemically, he finds that it consists of the elements carbon, oxygen, hydrogen, and nitrogen, with some sulphur. Phosphorus and some potash, soda and lime in small quantity, are also very usually associated with the elements named. These are combined in the protoplasm so as to form chemical compounds resembling and including white of egg, and are called "proteids." A chemical compound is a very definite and special thing, and when one says so-and-so is a definite chemical compound, one means that it is not a mere "mixture," but is composed of chemical elements (some out of the long list of about eighty indestructible, undecomposable, "simple" bodies—gases, liquids, metallic and non-metallic solids-recognised by chemists and known as such), peculiarly united to, or "combined" with, one another in definite proportions by weight.

Take, as an example, water. Water is a definite chemical compound, formed by the chemical union of two pure elements, the gases hydrogen and oxygeneighteen ounces of water consist of two ounces of hydrogen and sixteen ounces of oxygen. At a tem

perature above that of boiling water the gases, when they unite, contract to form water-vapour, three pints of the uniting gases (consisting of two pints of hydrogen and one of oxygen) forming two pints only of watervapour. This, when it is cooled to a temperature below 212 deg. Fahr., suddenly contracts to a few thimblefuls of pure liquid water. Neither oxygen nor hydrogen "uncombined" liquefy till far below zero.

A proteid, in the same way, is a chemical combination of the elements already mentioned-carbon, oxygen, hydrogen, nitrogen, and sulphur-but the proportions by volume of these elements to each other are represented by very high figures, not merely by two to one, as in the case of water. It is the carbon in them that makes "proteids" turn black when they are destroyed by burning, and it is the sulphur which causes the smell of rotten eggs. Whilst an ultimate molecule or physical particle of water consists of two atoms of hydrogen and one of oxygen the molecule of the proteid called "albumen" is built up by seventy-two atoms of carbon, one hundred and twelve atoms of hyrodgen, eighteen atoms of nitrogen, twelve atoms of oxygen, all brought into relation with one atom of sulphur. Probably in some other proteids the number of these atoms must all be multiplied by three. The elaborate "atomic composition of a molecule of proteid renders it very unstable; it easily falls to pieces, the elements combining, in other and simpler proportions, to form less "delicate" bodies. Living protoplasm consists chiefly of proteids and of compounds which are on the way up, forming step by step more elaborate combinations till they reach the proteid stageand of many others which are degradation products, coming down, as it were, from the giddy heights of the proteid combination. The protoplasm of a cell contains finer and grosser granules, which are these ascending