Reaction. Mechanical, physical (alias heat, etc.) reaction is exhausted with each occurrence of reaction. Chemical reaction alters the composition of the reacting body and is only renewed if a further quantity of the latter is added. Only the organic body reacts independently of course within its sphere of power (sleep), and assuming the supply of nourishment but this supply of nourishment is effective only after it has been assimilated, not immediately as at lower stages, so that here the organic body has an independent power of reaction, the new reaction must be mediated by it. Life and death. Already no physiology is held to be scientific if it does not consider death as an essential element of life (note, Hegel, Enzyklop die, I, pp. 152-53), the negation of life as being essentially contained in life itself, so that life is always thought of in relation to its necessary result, death, which is always contained in it in germ. The dialectical conception of life is nothing more than this. But for anyone who has once understood this, all talk of the immortality of the soul is done away with. Death is either the dissolution of the organic body, leaving nothing behind but the chemical constituents that formed its substance, or it leaves behind a vital principle, more or less the soul, that then survives all living organisms, and not only human beings. Here, therefore, by means of dialectics, simply becoming clear about the nature of life and death suffices to abolish an ancient superstition. Living means dying. Generatio quivoca.[spontaneous generation] All investigations hitherto amount to the following: in fluids containing organic matter in decomposition and accessible to the air, lower organisms arise, Protista, Fungi, Infusoria. Where do they come from? Have they arisen by generatio quivoca, or from germs brought in from the atmosphere? Consequently the investigation is limited to a quite narrow field, to the question of plasmogony. The assumption that new living organisms can arise by the decomposition of others belongs essentially to the epoch of immutable species. At that time men found themselves compelled to assume the origin of all organisms, even the most complicated, by original generation from non-living materials, and if they did not want to resort to the aid of an act of creation, they easily arrived at the view that this process is more readily explicable given a formative material already derived from the organic world; no one any longer believed in the production of a mammal directly from inorganic matter by chemical means. This assumption, however, directly conflicts with the present state of science. By the analysis of the process of decomposition in dead organic bodies chemistry proves that at each successive step this process necessarily produces products that are more and more dead, that are more and more close to the inorganic world, products that are less and less capable of being used by the organic world, and that this process can be given another direction, such utilisation being able to occur only when these products of decomposition are absorbed early enough in an appropriate, already existing, organism. It is precisely the most essential vehicle of cell-formation, protein, that decomposes first of all, and so far it has never been built up again. Still more. The organisms whose original generation from organic fluids is the question at issue in these investigations, while being of a comparatively low order, are nevertheless definitely differentiated, bacteria, yeasts, etc., with a life-cycle composed of various phases and in part, as in the case of the Infusoria, equipped with fairly well developed organs. They are all at least unicellular. But ever since we have been acquainted with the structureless Monera, it has become foolish to desire to explain the origin of even a single cell directly from dead matter instead of from structureless living protein, to believe it is possible by means of a little stinking water to force nature to accomplish in twenty-four hours what it has cost her thousands of years to bring about. Pasteur s experiments in this direction are useless; for those who believe in this possibility he will never be able to prove the impossibility by these experiments alone, but they are important because they furnish much enlightenment on these organisms, their life, their germs, etc. Liebig s statement to Wagner towards the end of his life (1868): Liebig said further (Wagner believes November 1868) Helmholtz (Preface to Thomson s Handbuch der theoretischen Physik, German edition, part II): Wagner: Worth noting is the proof how much of a dilettante Liebig was in biology, although the latter is a science bordering on chemistry. Comments. The above hypothesis of eternal life and of importation presupposes: Ad. 1. Liebig s assertion that carbon compounds are just as eternal as carbon itself, is doubtful, if not false. (a) Is carbon simple? If not, it is as such not eternal. (b) The compounds of carbon are eternal in the sense that under the same conditions of mixture, temperature, pressure, electric potential, etc., they are always reproduced. But that, for instance, only the simplest carbon compounds, CO2 or CH4, should be eternal in the sense that they exist at all times and more or less in all places, and not rather that they are continually produced anew and pass out of existence again in fact, out of the elements and into the elements has hitherto not been asserted. If living protein is eternal in the same sense as other carbon compounds, then it must not only continually be dissolved into its elements, as is well known to happen, but it must also continually be produced anew from the elements and without the collaboration of previously existing protein and that is the exact opposite of the result at which Liebig arrives. (c) Protein is the most unstable carbon compound known to us. It decomposes as soon as it loses the capacity of carrying out the functions peculiar to it, which we call life, and it is inherent in its nature that this incapacity should sooner or later make its appearance. And it is just this compound which is supposed to be eternal and able to endure all the changes of temperature, pressure, lack of nourishment, and air, etc., in space, although even its upper temperature limit is so low less than 100 C! The conditions for the existence of protein are infinitely more complicated than those of any other known carbon compound, because not only physical and chemical functions, but in addition nutritive and respiratory functions, enter, requiring a medium which is narrowly delimited, physically and chemically and is it this medium that one must suppose has maintained itself from eternity under all possible changes? Liebig prefers, ceteris paribus, the simpler of two hypotheses, but a thing may appear very simple and yet be very complicated. The assumption of innumerable continuous series of living protein bodies, tracing their descent from one another through all eternity, and which under all circumstances always leave sufficient over for the stock to remain well assorted, is the most complicated assumption possible. Moreover, the atmospheres of the heavenly bodies, and especially nebular atmospheres, were originally glowing hot and therefore no place for protein bodies; hence in the last resort space must serve as the great reservoir a reservoir in which there is neither air nor nourishment, and with a temperature at which certainly no protein can function or maintain itself! Ad. 2. The vibrios, micrococci, etc., which are referred to here, are beings already considerably differentiated protein granules that have excreted an outer membrane, but no nucleus. The series of protein bodies capable of development, however, forms a nucleus first of all and becomes a cell the cell membrane is then a further advance (Am ba Sph rococcus). Hence the organisms under consideration here belong to a series which, by all previous analogy, proceeds barrenly into a blind alley, and they cannot be numbered among the ancestors of the higher organisms. What Helmholtz says of the sterility of attempts to produce life artificially is pure childishness. Life is the mode of existence of protein bodies, the essential element of which consists in continual metabolic interchange with the natural environment outside them, and which ceases with the cessation of this metabolism, bringing about the decomposition of the protein. [Such metabolism can also occur in the case of inorganic bodies and in the long run it occurs everywhere, since chemical reactions take place, even if extremely slowly, everywhere. The difference, however, is that inorganic bodies are destroyed by this metabolism, while in organic bodies it is the necessary condition for their existence. Note by Engels.] If success is ever attained in preparing protein bodies chemically, they will undoubtedly exhibit the phenomena of life and carry out metabolism, however weak and short-lived they may be. But it is certain that such bodies could at most have the form of the very crudest Monera, and probably much lower forms, but by no means the form of organisms that have become differentiated by an evolution lasting thousands of years, and in which the cell membrane has become separated from the contents and a definite inherited form assumed. So long, however, as we know no more of the chemical composition of protein than we do at present, and therefore for probably another hundred years to come cannot think of its artificial preparation, it is ridiculous to complain that all our efforts, etc., have failed! Against the above assertion that metabolism is the characteristic activity of protein bodies may be put the objection of the growth of Traube s artificial cells.  But here there is merely unaltered absorption of a liquid by endosmosis, while metabolism consists in the absorption of substances, the chemical composition of which is altered, which are assimilated by the organism, and the residua of which are excreted together with the decomposition products of the organism itself resulting from the life process. [N.B. Just as we have to speak of invertebrate vertebrates, so also here the unorganised, formless, undifferentiated granule of protein is termed an organism dialectically this is permissible because just as the vertebral column is implicit in the notochord so in the protein granule on its first origin the whole infinite series of higher organisms lies included in itself as if in embryo Note by Engels] The significance of Traube s cells lies in the fact that they show endosmosis and growth as two things which can be produced also in inorganic nature and without any carbon. The newly arisen protein granule must have had the capacity of nourishing itself from oxygen, carbon dioxide, ammonia, and some of the salts dissolved in the surrounding water. Organic nutritive substances were not present, for the granules surely could not devour one another. This proves how high above them are the present-day Monera, even without nuclei, living on diatoms, etc., and therefore presupposing a whole series of differentiated organisms. Dialectics of Nature references. Nature No. 294 et seq. Allman on Infusoria. Unicellular character, important. Croll on Ice Periods and Geological Time. Nature No. 326, Tyndall on Generatio. Specific decay and fermentation experiments. Protista. 1. Non-cellular, begin with a simple granule of protein which extends and withdraws pseudopodia in one form or another, including the Monera. The Monera of the present day are certainly very different from the original forms, since for the most part they live on organic matter, swallowing diatoms and Infusoria (i.e., bodies higher than themselves and which only arose after them), and, as H ckel s plate 1 shows, have a developmental history and pass through the form of non-cellular ciliate swarm-spores. The tendency towards form which characterises all protein bodies is already evident here. This tendency is more prominent in the non-cellular Foraminifera, which excrete highly artistic shells (anticipating colonies? corals, etc.) and anticipate the higher molluscs in form just as the tubular Alg (Siphone ) anticipate the trunk, stem, root, and leaf form of higher plants, although they are merely structureless protein. Hence Protam ba is to be separated from Am ba. [in the margin: Individualisation small, they divide and also fuse."] 2. On the one hand there arises the distinction of skin (ectosarc) and medullary layer (endosarc) in the sun animalcule Actinophrys sol (Nicholson, p. 49). The epidermal layer puts out pseudopodia (in Protomyxa aurantiaca, this stage is already a transitional one, see H ckel, plate I). Along this line of evolution protein does not appear to have got very far. 3. On the other hand, the nucleus and nucleolus become differentiated in the protein naked Am b . From now on the development of form proceeds apace. Similarly, the development of the young cell in the organism, c.f. Wundt on this (at the beginning). In Am ba Sph rococcus, as in Protomyxa, the formation of the cell membrane is only a transitional phase, but even here there is already the beginning of the circulation in the contractile vacuole. (H ckel, p. 380.) Sometimes we find either a shell of sand grains stuck together (Difflugia, Nicholson, p. 47) as in worms and insect larv , sometimes a genuinely excreted shell. Finally, 4. The cell with a permanent cell membrane. According to H ckel (p. 382), out of this has arisen, depending on the hardness of the cell membrane, either plant, or in the case of a soft membrane, animal (? it certainly cannot be conceived so generally). With the cell membrane, definite and at the same time plastic form makes its appearance. Here again a distinction between simple cell membrane and excreted shell. But (in contrast to No. 3) the putting out of pseudopodia stops with this cell membrane and this shell. Repetition of earlier forms (ciliate swarm-spores) and diversity of form. The transition is provided by the Labyrinthule (H ckel, p. 385), which deposit their pseudopodia outside and creep about in this network with alteration of the normal spindle shape kept within definite limits. The Gregarin anticipate the mode of life of higher parasites some are already no longer single cells but chains of cells (H ckel, p. 451), but only containing 2-3 cells a weak beginning. The highest development of unicellular organisms is in the Infusoria, in so far as these are really unicellular. Here a considerable differentiation (see Nicholson). Once again colonies and zoophytes (Epistylis). Among unicellular plants likewise a high development of form (Desmidiace , H ckel, p. 410). [In the margin: Rudiment of higher differentiation"] 5. The next advance is the union of several cells into one body, no longer colony. First of all, the Katallakt of H ckel, Magosph ra Planula (H ckel, p. 384), where the union of the cells is only a phase in development. But here also there are already no pseudopodia (whether there are any as a transitional phase H ckel does not state exactly). On the other hand, the Radiolaria, also undifferentiated masses of cells, have retained their pseudopodia and have developed to the highest extent the geometric regularity of the shell, which plays a part even among the genuinely noncellular rhizopods. The protein surrounds itself, so to speak, with its crystalline form. 6. Magosph ra Planula forms the transition to the true Planula and Gastrula, etc. Further details in H ckel (p. 452 et seq.). Bathybius. The stones in its flesh are proof that the original form of protein, still lacking any differentiation of form, already bears within it the germ of and capacity for skeletal formation. The individual. This concept also has been dissolved into something purely relative. Cormus, colony, tapewormon the other hand, cell and metamere as individuals in a certain sense (anthropogeny and morphology). The whole of organic nature is one continuous proof of the identity or inseparability of form and content. Morphological and physiological phenomena, form and function, mutually determine one another. The differentiation of form (the cell) determines differentiation of substance into muscle, skin, bone, epithelium, etc., and the differentiation of substance in turn determines difference of form. Repetition of morphological forms at all stages of evolution: cell forms (the two essential ones already in Gastrula) metamere formation at a certain stage: annelids, arthropods, vertebrates. In the tadpoles of amphibians the primitive form of ascidian larv is repeated. Various forms of marsupials, which recur among placentals (even counting only existing marsupials). For the entire evolution of organism the law of acceleration according to the square of the distance in time from the point of departure is to be accepted. Cf. H ckel, Sch pfungsgeschichte and Anthropogenie, the organic forms corresponding to the various geological periods. The higher, the more rapid the process. The Darwinian theory to be demonstrated as the practical proof of Hegel s account of the inner connection between necessity and chance. The struggle for existence. Above all this must be strictly limited to the struggles resulting from plant and animal over-population, which do in fact occur at certain stages of plant and lower animal life. But one must keep sharply distinct from it the conditions in which species alter, old ones die out and newly evolved ones take their place, without this over-population: e.g., on the migration of animals and plants into new regions where new conditions of climate, soil, etc., bring about the alteration. If there the individuals which become adapted survive and develop into a new species by continually increasing adaptation, while the other more stable individuals die away and finally die out, and with them the imperfect intermediate stages, then this can and does proceed without any Malthusianism, and if the latter should occur here at all it makes no change to the process, at most it can accelerate it. Similarly with the gradual alteration of the geographical, climatic, etc., conditions in a given region (drying up of Central Asia for instance). Whether the members of the animal or plant population there exert pressure on one another is a matter of indifference; the process of evolution of the organisms that is determined by this alteration proceeds all the same. It is the same for sexual selection, in which case, too, Malthusianism is quite unconcerned. Hence also H ckel s adaptation and heredity can bring about the whole process of evolution, without need for selection and Malthusianism. Darwin s mistake lies precisely in lumping together in natural selection or the survival of the fittest  two absolutely separate things: The main thing: that each advance in organic evolution is at the same time a regression, fixing one-sided evolution and excluding the possibility of evolution in many other directions. This, however, a basic law. The struggle for life. Until Darwin, what was stressed by his present adherents was precisely the harmonious cooperative working of organic nature, how the plant kingdom supplies animals with nourishment and oxygen, and animals supply plants with manure, ammonia, and carbonic acid. Hardly was Darwin recognised before these same people saw everywhere nothing but struggle. Both views are justified within narrow limits, but both are equally one-sided and prejudiced. The interaction of bodies in nonliving nature includes both harmony and collisions, that of living bodies conscious and unconscious co-operation as well as conscious and unconscious struggle. Hence, even in regard to nature, it is not permissible one-sidedly to inscribe only struggle on one s banners. But it is absolutely childish to desire to sum up the whole manifold wealth of historical evolution and complexity in the meagre and one-sided phrase struggle for existence. That says less than nothing. The whole Darwinian theory of the struggle for existence is simply the transference from society to organic nature of Hobbes theory of bellum omnium contra omnes and of the bourgeois economic theory of competition, as well as the Malthusian theory of population. When once this feat has been accomplished (the unconditional justification for which, especially as regards the Malthusian theory, is still very questionable), it is very easy to transfer these theories back again from natural history to the history of society, and altogether too naive to maintain that thereby these assertions have been proved as eternal natural laws of society. Let us accept for a moment the phrase struggle for existence, for argument s sake. The most that the animal can achieve is to collect; man produces, he prepares the means of life, in the widest sense of the words, which without him nature would not have produced. This makes impossible any unqualified transference of the laws of life in animal societies to human society. Production soon brings it about that the so-called struggle for existence no longer turns on pure means of existence, but on means of enjoyment and development. Here where the means of development are socially produced the categories taken from the animal kingdom are already totally inapplicable. Finally, under the capitalist mode of production, production reaches such a high level that society can no longer consume the means of life, enjoyment and development that have been produced, because for the great mass of producers access to these means is artificially and forcibly barred; and therefore every ten years a crisis restores the equilibrium by destroying not only the means of life, enjoyment and development that have been produced, but also a great part of the productive forces themselves. Hence the so-called struggle for existence assumes the form: to protect the products and productive forces produced by bourgeois capitalist society against the destructive, ravaging effect of this capitalist social order, by taking control of social production and distribution out of the hands of the ruling capitalist class, which has become incapable of this function, and transferring it to the producing masses and that is the socialist revolution. The conception of history as a series of class struggles is already much richer in content and deeper than merely reducing it to weakly distinguished phases of the struggle for existence. Vertebrates. Their essential character: the grouping of the whole body about the nervous system. Thereby the development of self-consciousness, etc., becomes possible. In all other animals the nervous system is a secondary affair, here it is the basis of the whole organisation; the nervous system, when developed to a certain extent by posterior elongation of the head ganglion of the worms takes possession of the whole body and organises it according to its needs. When Hegel makes the transition from life to cognition by means of propagation (reproduction), there is to be found in this the germ of the theory of evolution, that, organic life once given, it must evolve by the development of the generations to a genus of thinking beings. What Hegel calls reciprocal action is the organic body, which, therefore, also forms the transition to consciousness, i.e., from necessity to freedom, to the idea. See Logik, II, conclusion. Rudiments in nature. Insect states (the ordinary ones do not go beyond purely natural conditions), here even a social rudiment. Ditto productive animals with tools (bees, etc., beavers), but still only subsidiary things and without total effect. Even earlier: colonies of corals and Hydrozoa, where the individual is at most an intermediate stage and the fleshy community mostly a stage of the full development. See Nicholson. Similarly, the Infusoria, the highest, and in part very much differentiated, form which a single cell can achieve. Work. The mechanical theory of heat has transferred this category from economics into physics (for physiologically it is still a long way from having been scientifically determined), but in so doing it becomes defined in quite a different way, as seen even from the fact that only a very slight, subordinate part of economic work (lifting of loads, etc.) can be expressed in kilogram-metres. Nevertheless, there is an inclination to re-transfer the thermodynamical definition of work to the sciences from which the category was derived, with a different determination. For instance, without further ado, to identify it crudely with physiological work, as in Fick and Wislicenus Faulhorn experiment, in which the lifting of a human body, of say 60 kgs., to a height of say 2,000 metres, i.e., 120,000 kilogram-metres, is supposed to express the physiological work done. In the physiological work done, however, it makes an enormous difference how this lifting is effected: whether by positive lifting of the load, by mounting vertical ladders, or whether along a road or stair with 45o slope (=militarily impracticable terrain), or along a road with a slope of 1/18, hence a length of about 36 kms. (but this is questionable, if the same time is allowed in all cases). At any rate, however, in all practicable cases a forward motion also is combined with the lifting, and indeed where the road is quite level this is fairly considerable and as physiological work it cannot be put equal to zero. In some places there even appears to be not a little desire to re-import the thermodynamical category of work back into economics (as with the Darwinists and the struggle for existence), the result of which would be nothing but nonsense. Let someone try to convert any skilled labour into kilogram-metres and then to determine wages on this basis! Physiologically considered, the human body contains organs which in their totality, from one aspect, can be regarded as a thermodynamical machine, where heat is supplied and converted into motion. But even if one presupposes constant conditions as regards the other bodily organs, it is questionable whether physiological work done, even lifting, can be at once fully expressed in kilogram-metres, since within the body internal work is performed at the same time which does not appear in the result. For the body is not a steam-engine, which only undergoes friction and wear and tear. Physiological work is only Possible with continued chemical changes in the body itself, depending also on the process of respiration and the work of the heart. Along with every muscular contraction or relaxation, chemical changes occur in the nerves and muscles, and these changes cannot be treated as parallel to those of coal in a steam-engine. One can, of course, compare two instances of physiological work that have taken place under other wise identical conditions, but one cannot measure the physical work of a man according to the work of a steam engine, etc.; their external results, yes, but not the processes themselves without considerable reservations. (All this has to be thoroughly revised.)
Notes and Fragments for Dialectics of Nature. Engels 1883