Life and death

by A. Dastre

Law of Connection of Two Orders of Vital Facts.—“These phenomena [of organic destruction and of assimilating synthesis] are simultaneously produced in every living being, in a connection which cannot be broken. The disorganization or dissimilation uses up living matter [by this we must understand the reserve-stuff, as will be seen later on in the quotation] in the organs in function: the assimilating synthesis regenerates the tissues; it gathers together the reserve-stuff which the vital activity must expend. These two operations of destruction and renovation, inverse the one to the other, are absolutely connected and inseparable, in this sense at any rate, that destruction is the necessary condition of renovation. The phenomena of functional destruction are themselves the precursors and the instigators of material regeneration, of the formative process which is silently going on in the intimacy of the tissues. The losses are repaired as they take place; and equilibrium being re-established as soon as it tends to be broken, the body is maintained in its composition.”

It is perfectly right and wise to say with Claude Bernard that the two orders of facts are successive, and that one is normally the inciting condition of the other. The possibility of the development of the yeast when fermentation fails, and the weakness of this development on the other hand under these conditions, are an excellent proof of this. The one proves the essential independence of the two orders of facts, the other the inciting and provoking virtue of the first relatively to the second. The experimental truth is thus expressed with a minimum of uncertainty. We know the facts which led Le Dantec to formulate his law of functional assimilation—namely, that the functional activity is useful or indispensable to the growth of the organ; that the organs which are functionally active grow, and those which do not act become atrophied. We are only expressing the facts when we say that the organic destructions that go on in the living being (whether at the expense of its reserve-stuff or at the expense of its medium, or whether it be even slightly at the expense of the plastic substance itself) are the antecedent, the inciting agent or the normal condition of the chemical and organogenic syntheses which create the new protoplasm.

On the other hand, we are wrong if we hold with Le Dantec that instead of two chemical operations there is only one, that which creates the new protoplasm. The obvious destruction is neglected; it is deliberately passed over. He does not see that it is necessary to liberate the energy employed in the construction, by complication, of this highly complex substance which is the new protoplasm. He really seems to have made up his mind not to analyze the phenomenon. If we decline to admit that to the first act of functional destruction succeeds a second, assimilation or organogenic synthesis, we are looking at elementary beings, in which the succession cannot be grasped, as we look on brewers’ yeast. We not only mean that the morphogenic assimilation results from the functional activity; we mean that it results from it directly, immediately, that it is the functional activity itself. Experiment tells us nothing of all this. It shows us the real facts, the facts of the destruction of an organic immediate principle, the sugar, and the fact that an assimilating synthesis is the correlative of this destruction. Besides, if it is impossible in examples of this kind to exhibit the succession, it is perfectly easy in beings of a higher order. It is, then, clearly seen that the preliminary destruction of a reserve-stuff (and perhaps of a small quantity of the living substance) precedes and conditions the formation of a greater quantity of this living matter—in other words, the growth of the protoplasm of the organ.

Contradictions in the New Theory.—Moreover, these mistakes involve those who make them in a series of inextricable contradictions. Here, for example, is life; it is found, they say, in three forms:—Life manifested, or condition 1º; latent life, or condition 3º. So far this is the classical theory; but they add a condition 2º, which is what might be called pathological or incomplete life. This is defined by the following characteristic:—That its functional phenomena are identical with those in the first form, but that they are not accompanied by assimilation and by protoplasmic growth, But since, they say, growth is the chemical consequence of the functional activity, since it is so to speak its metabolic aspect, since it is confused with it, and inseparable from it, by the argument—then it is contradictory and logically absurd to speak of condition 2º. It would be acknowledging in the case of the anucleated merozoite, for example, a functional activity unaccompanied by assimilation, yet identical with the functional activity which is accompanied by assimilation in the nucleated merozoite. The general movement, that of the cilia, the taking of food, the evacuation of the fæces, the contraction of the pulsatile vacuoles, are the same. And this fact is the best proof that this vital functional activity (with the organic destruction which is its energetic source) must be distinguished from the assimilation which usually follows it, and which in exceptional cases may not follow it.

We shall carry this discussion no farther. We have examined at some length Le Dantec’s views, and we have contrasted them with the doctrine which has been current in general physiology since the time of Claude Bernard, and this comparison does not turn out quite to their advantage. It was inevitable that the experimental and realistic spirit which inspired the doctrine of the celebrated physiologist made his work really too systematic. His formula, “life is death,” and the form he gave his ideas, are not always irreproachably correct. They lend themselves at times to criticism. Sometimes they require commentary. These are errors of detail which Le Dantec has summarized somewhat roughly. There is no necessity to do this in his own case. We pay our tribute to the clearness of his language, although we believe the foundations of his system are false and ill-founded. Their rigour is purely verbal. Their external qualities, their careful arrangement are well adapted to the seduction of the systematic mind prepared by mathematical teaching. This new theory of life is presented with pedagogic talent of the highest order. We think we have shown that the foundations are entirely fallacious, in particular the following:—Vital condition No. 2º; the confusion between functional activity and assimilating synthesis; the so-called absolute connection between morphogeny and chemical composition; the fundamental distinction between elementary life and individual life.

§ 4. Characteristics of Nutrition.

Definition of Nutrition.—As we have just seen, the organism is the scene of chemical reactions of two kinds, the one destructive and simplifying, the other synthetic, constructive, or assimilating. This totality of reactions constitutes nutrition. Hence the two phases that it is convenient to consider in this function—assimilation and disassimilation. This twofold chemical movement or metabolism corresponding to the two categories of vital phenomena, of destruction (catabolism) and of synthesis (anabolism) is therefore the chemical sign of vitality in all its forms. But it is clear that disassimilation or organic destruction, which is destined to furnish energy to the organism for its different operations, reappears in the plan of the general phenomena of nature. It is not specifically vital in its principle. Assimilation, on the other hand, is in this respect much more characteristic.

To some physiologists nutrition is only assimilation. Of the two aspects of metabolism they consider only one, the most typical, Ad-similare, to assimilate, to restore the substance borrowed from the ambient medium, the alimentary substances, similar to living matter, to make living matter of them, to increase active protoplasm—this is indeed the most striking phenomenon of vitality. To grow, to increase, to expand, to invade, is the law of living matter. Assimilation, nutrition in its essentials, is, according to the definition of Ch. Robin, “the production by the living being of a substance identical with its own.” It is the act by which the living matter, the protoplasm of a given being, is created.

Permanence in Nutrition.—Nutrition presents one quite remarkable character—permanence. It is a vital manifestation, a property if we look at it in the cell, in the living substance, a function if we consider it in the animal or in the plant as a whole, which is never arrested. Its suspension involves ipso facto the suspension of life itself. It is, in the words of Claude Bernard, that property of nutrition “which, as long as it exists in an element, compels us to believe that this element is alive, and which, when it is absent, compels us to believe that it is dead. It dominates all others by its generality and its importance. In a word, it is the absolute test of vitality.”

Biological Energetics shows the Importance of Nutrition.—We have indicated in advance the reason of its importance, showing that its two phases, disassimilation and assimilation, are the energetic condition of the two kinds of vital phenomena which we can distinguish.