The Wonders of Life: A Popular Study of Biological Philosophy. Ernst Haeckel
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chromacea (phycochromacea or cyanophycea), and especially the simplest forms of these, the chroococcacea (chroococcus, aphanocapsa, glœocapsa, etc.). These plasmodomous (plasma-forming) monera, which live at the very frontier of the organic and inorganic worlds, are by no means uncommon or particularly difficult to find; on the contrary, they are found everywhere, and are easy to observe. Yet they are generally ignored because they do not square with the prevailing dogma of the cell.
I ascribe this special significance to the chromacea among all the monera I have instanced because I take them to be the oldest phyletically, and the most primitive of all living organisms known to us. In particular their very simple forms correspond exactly to all the theoretic claims which monistic biology can make as to the transition from the inorganic to the organic. Of the chroococcacea, the chroococcus, glœocapsa, etc., are found throughout the world; they form thin, usually bluish-green coats or jelly-like deposits on damp rocks, stones, bark of trees, etc. When a small piece of this jelly is examined carefully under a powerful microscope, nothing is seen but thousands of tiny blue-green globules of plasma, distributed irregularly in the common structureless mass. In some species we can detect a thin structureless membrane enclosing the homogeneous particle of plasm; its origin can be explained on purely physical principles by "superficial energy"—like the firmer surface-layer of a drop of rain, or of a globule of oil swimming in water. Other species secrete homogeneous jelly-like envelopes—a purely chemical process. In some of the chromacea the blue-green coloring matter (phyocyan) is stored in the surface-layer of the particle of plasm, while the inner part is colorless—a sort of "central body." However, the latter is by no means a real, chemically and morphologically distinct, nucleus. Such a thing is completely lacking. The whole life of these simple, motionless globules of plasm is confined to their metabolism (or plasmodomism, chapter x.) and the resulting growth. When the latter passes a certain stage, the homogeneous globule splits into two halves (like a drop of quicksilver when it falls). This simplest form of reproduction is shared by the chromacea (and the cognate bacteria) with the chromatella or chromatophora, the green particles of chlorophyll inside ordinary plant-cells; but these are only parts of a cell. Hence no unprejudiced observer can compare these unnucleated and independent granules of plasm with real (nucleated) cells, but must conceive them rather as cytodes. These anatomic and physiological facts may easily be observed in the chromacea, which are found everywhere. The organism of the simplest chromacea is really nothing more than a structureless globular particle of plasm; we cannot discover in them any composition of different organs (or organella) for definite vital functions. Such a composition or organization would have no meaning in this case, since the sole vital purpose of these plasma-particles is self-maintenance. This is attained in the simplest fashion for the individual by metabolism; for the species it is effected by self-cleavage, the simplest conceivable form of reproduction.
Modern histologists have discovered a very intricate and delicate structure in many of the higher unicellular protists and in many of the tissue-cells of the higher animals and plants (such as the nerve-cells). They wrongly conclude that this is universal. In my opinion, this complication of the structure of the elementary organism is always a secondary phenomenon, the slow and gradual result of countless phylogenetic processes of differentiation, initiated by adaptation and transmitted to posterity by heredity. The earliest ancestors of all these elaborate nucleated cells were at first simple, unnucleated cytodes, such as we find to-day in the ubiquitous monera. We shall see more about them in the ninth and fifteenth chapters.
Naturally, this lack of a visible histological structure in the plasma-globule of the monera does not exclude the possession of an invisible molecular structure. On the contrary, we are bound to assume that there is such a structure, as in all albuminoid compounds, and especially all plasmic bodies. But we also find this elaborate chemical structure in many lifeless bodies; some of these, in fact, show a metabolism similar to that of the simplest organisms. We will return subsequently to this subject of catalysis. Briefly, the only difference between the simplest chromacea and inorganic bodies that have catalysis is in the special form of their metabolism, which we call plasmodomism (formation of plasm), or "carbon-assimilation." The mere fact that the chromacea assume a globular form is no sign whatever of a morphological vital process; drops of quicksilver and other inorganic fluids take the same shape when the individual body is formed under certain conditions. When a drop of oil falls into a fluid of the same specific gravity with which it cannot mix (such as a mixture of water and spirits of wine), it immediately assumes a globular shape. Inorganic solids usually take the form of crystals instead. Hence the distinctive feature of the simplest organism, the plasma-particles of the monera, is neither anatomic structure nor a certain shape, but solely the physiological function of plasmodomism—a process of chemical synthesis.
The difference between the monera I have described and any higher organism is, I think, greater in every respect than the difference between the organic monera and the inorganic crystals. Nay, even the difference between the unnucleated monera (as cytodes) and the real nucleated cells may fairly be regarded as greater still. Even in the simplest real cell we find the distinction between two different organella, or "cell-organs," the internal nucleus and the outer cell-body. The caryoplasm of the nucleus discharges the functions of reproduction and heredity; the cytoplasm of the cell-body accomplishes the metabolism, nutrition, and adaptation. Here we have, therefore, the first, oldest, and most important process of division of labor in the elementary organism. In the unicellular protists the organization rises in proportion to the differentiation of the various parts of the cell; in the tissue-forming histona it rises again in proportion to the distribution of work (or ergonomy) among the various organs. Darwin has given us in his theory of selection a mechanical explanation of the apparent design and purposiveness in this.
In order to have a correct monistic conception of organization, it is important to distinguish the individuality of the organism in its various stages of composition. We shall treat this important question, about which there is a good deal of obscurity and contradiction, in a special chapter (vii.). It suffices for the moment to point out that the unicellular beings (protists) are simple organisms both in regard to morphology and physiology. On the other hand, this is only true in the physiological sense of the histona, the tissue-forming animals and plants. From the morphological point of view they are made up of innumerable cells, which form the various tissues. These histonal individuals are called sprouts in the plant world and persons in the animal world. At a still higher stage of organization we have the trunk or stem (cormus), which is made up of a number of sprouts or persons, like the tree or the coral-stem. In the fixed animal stems the associated individuals have a direct bodily connection, and take their food in common; but in the social aggregations of the higher animals it is the ideal link of common interest that unites the individuals, as in swarms of bees, colonies of ants, herds of mammals, etc. These communities are sometimes called "animal-states." Like human polities, they are organisms of a higher type.
However, in order to avoid misunderstanding, we must take the word "organism" in the sense in which most biologists use it—namely, to designate an individual living thing, the material substratum of which is plasm or "living substance"—a nitrogenous carbon-compound in a semi-fluid condition. It leads to a good deal of misunderstanding when separate functions are called organisms, as is done sometimes in speaking of the soul or of speech. It would be just as correct to call seeing or running an organism. It is advisable also in scientific treatises to refrain from calling inorganic compounds as such "organisms," as, for instance, the sea or the whole earth. Such names, having a purely symbolical value, may very well be used in poetry. The rhythmic wave-movement of the ocean may be regarded as its respiration, the surge as its voice, and so on. Many scientists (like Fechner) conceive the whole earth with all its organic and inorganic contents as a gigantic organism, whose countless organs have been arranged in an orderly whole by the world-reason (God). In the same way the physiologist, Preyer, regards the glowing heavenly bodies as "gigantic organisms, whose breath is, perhaps, the glowing vapor of iron, whose blood is liquid metal, and whose food may be meteorites." The danger of this poetic application of the metaphorical sense of organism is very well seen in this instance, as Preyer builds on it a quite untenable hypothesis of the origin of life (see chapter xv.).
In the wider sense the word "organic" has long been used in chemistry as an antithesis to inorganic. By organic