Life and death

by A. Dastre

It is very remarkable that all this profound knowledge of structure has been so sterile from the point of view of the knowledge of cellular functional activity. All that is known of the life of the cell has been revealed by experiment. Nothing has resulted from microscopic observation but ideas as to configuration. When it is a question of giving or imagining an explanation of vital facts, of heredity, etc., biologists unable to supply anything beyond the details of structure revealed by anatomy have had recourse to hypothetical elements, gemmules, pangenes, biophores, and different kinds of determinants.

Anatomy never has explained and never will explain anything. “Happy physicists!” wrote Loeb, “in never having known the method of research by sections and stainings! What would have happened if by chance a steam engine had fallen into the hands of a histological physicist? How many thousands of sections differently stained and unstained, how many drawings, how many figures, would have been produced before they knew for certain that the machine is an engine, and that it is used for transforming heat into motion!”

The study of physical properties, continued on rational hypotheses, has also thrown some light on the possible constitution of living matter. The gap between microscopical structure and molecular or chemical structure has thus been filled.

The consideration of the properties of turgescence and of swelling, which very generally belong to organized tissues, and therefore to the organic substance of protoplasm, has enabled us to obtain some idea of its ultra-microscopic constitution. If we wet a piece of sugar or a morsel of salt, before they are dissolved they absorb and imbibe the water without sensibly increasing their volume. It is quite otherwise with a tissue (i.e., with a protoplasm) when weakened in water as a preliminary. The tissue, plunged into the liquid, absorbs it, swells, and often grows considerably. And this water does not lodge in the gaps, in pre-existing lacunar spaces, for organic matter presents no gaps of this kind. It does not resemble a porous mass with capillary canals, such as sandstone, tempered mortar, clay, or refined sugar. The molecules of water interpose between and separate the organic molecules, thus increasing by a sort of intussusception the intervals separating the one from the other—molecular intervals escaping the senses, as do the molecules themselves because they are of the same order of magnitude.

Micellar Theory.—While pondering over this phenomenon, an eminent physiologist, Nägeli, was led in 1877 to propose his micellar theory. Micellæ are groups of molecules in the sense in which physicists and chemists use the word. They are molecular structures with a configuration. They rapidly absorb water and are capable of fixing a more or less thick and adherent layer of it to their surface. In a word, they are aggregates of organic matter and water.

There is therefore every reason for believing that the microsomes of spongy protoplasm, the physical support or basis of cellular life, are groups of micellæ formed of albuminoid substances and water. These clustered forms, these micellæ, are not absolutely peculiar to organized matter. Pfeffer, the learned botanist, has pointed them out under another name, tagmata, in the membranes of chemical precipitates.

Beyond this limit analysis finds nothing but the chemical molecule and the atom. So that if we wish to reconstruct the hierarchy of the materials of constitution of the protoplasm in order of ascending complexity, we shall find at the foundation the atom or atoms of simple bodies. They are principally carbon, hydrogen, oxygen, nitrogen, the elements of all organic compounds, to which may be added sulphur and phosphorus. At the head we have the albuminoid molecule, or the albuminoid molecules, aggregates of the preceding atoms. In the third stage the micellæ or tagmata, aggregates of albuminoids and water, are still too small to be observed by the senses. They unite in their turn to form the microsomes, the first elements visible to the microscope. The microsomes, cemented by linin, form the filaments or links which are called mitomes. The living protoplasm is therefore nothing but a chain, or tangled skein, or a spongy skeleton formed by its filaments.

Such is the typical constitution of living matter according to microscopic observation, supplemented by a perfectly reasonable hypothesis, which is, so to speak, only a translation of one of its most evident physical properties. This relatively simple scheme has become a complex scheme in the hands of later biologists. On the micellar hypothesis, which seems almost inevitable in its character, new hypotheses have been grafted, merely for the sake of convenience. Hence, we are led farther and farther from the real truth, and this is why, in order to explain the phenomena of heredity, we find ourselves compelled to intercalate hypothetical elements between micellæ and the microsome in the higher hierarchy quoted above—gemmules, pangenes, plasomes, which are only mental pictures or simple images to represent them.

§ 4. The Individuality of Complex Beings. Law of the Constitution of Organisms.

Individuality of Complex Beings.—From the cellular doctrine follows a remarkably suggestive conception of living beings. The metazoa and the metaphytes—that is to say, the multicellular living beings which may be seen with the eyes and do not require the microscope to reveal them—are an assemblage of anatomical elements and the posterity of a cell. The animal or the plant, instead of being an individual unity, is a “multitude,” a term which is used by Goëthe himself when pondering, in 1807, over the doctrine taught by Bichat; or, according to the equally correct expression of Hegel, it is a “nation”; it springs from a common cellular ancestor, just as the Jewish people sprang from the loins of Abraham.