Life and death

by A. Dastre

The majority of physiologists, following Claude Bernard, admit as valent and convincing the proof that the illustrious experimenter furnished of this unity of the vital processes. There are, however, a few voices crying in the wilderness. M. Le Dantec is one. In his new theory of life he amplifies and exalts the differences which exist between the elementary life of the proteids and the associated life of the metazoa. In them he can see nothing but contrasts and deviations.

If this is elementary life, let us ask what is elementary death—i.e., the death of the cell. And in this connection let us ask the questions which we have to examine in the case of animals high in organization, and of man himself. What are the characteristics of elementary death? When the cell dies, is its death preceded by a growing old or senescence? What are the preliminary signs and the acknowledged symptoms?

Changes Produced by Death.—The state of death is only truly realized when the fundamental properties of living matter enumerated above have entirely disappeared. We must follow step by step this disappearance in all the anatomical elements of the metazoan.

Now the properties of the cell are connected with the physical and chemical organization of living matter. For them to disappear entirely, this organization must be destroyed as far as all that is essential in it is concerned. We cannot admit with the vitalists that there is any material difference between the dead and the living, and that only an immaterial principle which has escaped into the air distinguishes the corpse from the animated being. In fact, the external configuration may be almost preserved, and the corpse may bear the aspect and the forms of the preceding state. But this appearance is deceptive. Something in reality has changed. The structure, the chemical composition of the living substance, have undergone essential changes. What are these changes?

Physical Changes.—Certain physiologists have endeavoured to determine them. Klemm, a botanist, pointed out in 1895 the physical changes which characterize the death of vegetable cells—loss of turgescence, fragmentation of the protoplasm, the formation of granules, and the appearance of vacuoles.

Chemical Changes.—O. Loew and Bokorny laid great stress in 1886 and 1896 on the chemical changes. The living protoplasm according to them is an unstable proteid compound. A slight change would detach from the albuminoid molecule a nucleus with the function of aldehyde, and at the same time would transform an amido-group into an amido-group. This would suffice for the transition of the protoplasm from the living to the dead state. This theory is based on the fact that the compounds which exercise a toxic action on the living cell, without acting chemically on the dead albumin, are easily fixed by the aldehydes; and on the fact that many of them, which attack simultaneously the living albuminoids and the dead albumin, easily combine with the amido-group.

E. Pflüger, a celebrated German scientist, has considered living matter as an albumin spontaneously decomposable, the essential nucleus of which is formed by cyanogen. Its active instability would be due to the penetration into the molecule of the oxygen which fixes on the carbon and separates it from the nitrogen. Armand Gautier has not confirmed this view. Duclaux (1898) has stated that the difference between the living and the dead albumin would be of a stereochemical order.

Progressive Character of Death. Accidental Death.—We have seen that in general the disappearance of the characteristics of vitality is not instantaneous, at least in the natural course of things, in complex organisms. It is the end of a more or less rapid process. But death is not instantaneous in the isolated anatomical element any more than it is in the protozoan or protophyte. We must have recourse to very violent devices of destruction to kill the cell at a blow, to leave absolutely nothing of its organization existing. The protoplasm of yeast when violently crushed by Büchner still possessed the power of secreting soluble ferments. A powerful action, a very high temperature, is necessary to obtain the result. A fortiori, the difficulty increases in the case of complex organisms, all of whose living elements cannot be attacked at the same moment by the destructive cause. A mechanical action, capable of destroying at one blow all the living parts of a complex being, of an animal, of a plant, must be of almost inconceivable power. The blow of a Nasmyth hammer would not be strong enough.

The chemical alteration produced by a very toxic substance distributed throughout the blood, and thus brought into contact with each element, would produce a disorganization which, however rapid it were, could not be called instantaneous. And the same holds good of physical agents.

But these are not the processes of nature under normal circumstances. They are accidents or devices. We shall leave on one side their consideration and we shall only deal here with the natural processes of the organism.