CHAPTER IV BIOLOGY

 The passage from the inorganic world to the world of Life constitutes a critical step in natural philosophy. Astronomy, Physics, and Chemistry represented successive steps in the same series. If each order of phenomena presented in itself something which was irreducible to previous orders, nevertheless all these phenomena, in a certain sense, remained homogeneous. Without rashness, Descartes could conceive that physics, like astronomy, would one day assume the mathematical form. And to-day more than one scientific man considers the distinction between physics and chemistry as provisional.   But as soon as life appears, we enter a new world. At this degree the “enrichment of the real” is suddenly so considerable that we find it difficult to admit the homogeneity of these phenomena with the preceding ones. Comte here reaps the benefit of his prudence. His philosophy has guarded against reducing all science to a single type, and it is content with the unity of method and the homogeneity of doctrine. It only demands that each science should limit itself to the search after the laws of phenomena. As to the way in which this research is to be carried out, it is evidently subordinated to the nature of the phenomena in question. Now, biological phenomena present a number of characteristics which belong to them alone, and the first duty of the positive science which studies them is to respect their originality.   172   Comte, therefore, here breaks with Descartes who conceived biology as a prolongation of physics. He takes an entirely different view of this science, which, in a sense, is opposed to the whole of the sciences of the inorganic world. From this there arises a double effort. On the one hand, Comte wishes to maintain the continuity of the encyclop?dic series of the sciences: he thus shows Biology as immediately following chemistry, and maintaining the closest relations with astronomy and physics. On the other hand he clearly brings out the irreducible character of the vital phenomena, and the modifications which the positive method must undergo when applied to them. Despite the extreme difference between the points of view and the doctrines, he often makes us think of those deep and difficult passages in the Critique du Jugement where Kant has shown that without the hypothesis of an inner finality, (although this hypothesis is in itself obscure), the phenomena which take place in living beings remain unintelligible.   With biology, says Comte, necessarily appear the ideas of consensus, of hierarchy, of “milieu”, of the conditions of existence, of the relation between the static and the dynamic states, between the organ and the function.154 In a word, a biological phenomenon, considered alone is devoid of meaning. Strictly speaking, it does not even exist. It can only be understood by its relations with the other phenomena which take place in the living being, phenomena which react upon it. At the same time it reacts upon them. Here, in opposition to what takes place in the inorganic world, the parts are only intelligible through the idea of the whole. Undoubtedly a certain solidarity of phenomena exists in the inorganic world, which allows us to consider united wholes in it. But the solidarity of biological phenomena is far closer, for, without it we could not conceive them, while, as regards the phenomena of the173 inorganic world, there is nothing impossible in this abstraction.   Henceforth, the positive method must adapt itself to the characteristics which belong to biological phenomena. It does not always demand, as it has been wrongly stated, that we should go from the simple to the complex, but only that we should proceed from the known to the unknown. It is true that in the sciences of the inorganic world we proceed from the least complex to the most complex cases; we begin by the study of phenomena which are as isolated as possible from one another. But, on the contrary, living beings are all the better known to us in proportion as they are more complex. The idea of the animal is in some respects clearer to us than the idea of the vegetable. The idea of the superior animals is clearer to us than that of the inferior ones. Finally man for us is the principal biological unity, and it is from this unity that speculation starts in this science.   Thus, in dealing with Biology the positive method undergoes a veritable inversion. In the preceding sciences, the last degree of composition is forbidden us: we never succeed in uniting the whole of the inorganic world into a single synthesis. In biology, on the contrary, sums of phenomena are given; but it is the last degree of simplicity which escapes us. We have to start from those sums of phenomena, and biology must in this way assume a synthetic character. In it the analysis of phenomena will be as minute as possible; but the analytical operations will always be more or less directly subordinated to the leading idea of the vital consensus.155 II.   Like the other fundamental sciences Biology must be abstract, that is to say it must not bear upon individual beings, but upon174 phenomena. It is thus distinct from zoology and botany which are concrete sciences. In its widest generality it is defined through the constant correspondence between the anatomical and the physiological point of view. Its object is to constantly unite them to one another. In reality these two points of view are the two aspects of a single problem. It is owing to historical reasons that, during a certain time, these two sciences appeared to develop independently of one another. Physiology remained attached to the metaphysical methods, that is to say, to unverifiable hypotheses and to principles which went beyond experience, while anatomists already made use of the positive method. But to-day, the two sciences being equally positive, “their opposition is reduced to that which subsists between the static and the dynamic points of view.”156   Another element which should enter into the more general definition of biology, although it has sometimes been neglected, is the consideration of the milieu. The relation between the organism and its milieu is no less essential to life than the relation of the organ to the function. Life supposes not only that the being should be organised in a certain way, but also that a certain number of external circumstances should sustain this organisation, and should be compatible with its activity. Living beings are thus dependent upon their milieu, and this dependence grows as we rise in the organic series. The system of the conditions of existence becomes all the more complex as the functions develop and become more varied. Inferior organisms are subject to less numerous external conditions; but, says Comte, a little variation in one of these conditions suffices to make them perish. The superior organisms stand a variation of this kind better. But, in return, the number of conditions upon which they depend is far greater. The study of milieux in their relations175 to organisms, a study which is hardly outlined, undoubtedly has many discoveries in store for the future.157 Here is an order of problems of which Lamarck probably suggested the idea to Comte, and upon which Darwin’s genius will work.   Bichat then was wrong in saying in his celebrated definition of life that it is “the sum of the forces which resist death.” The radical antagonism between inorganic and living nature is an incomplete and consequently a false idea. Indeed if, as Bichat supposed, everything which surrounds living bodies tended to destroy them, their existence would become unintelligible.158 Where could they find strength to resist such formidable pressure, even for a short time? On the contrary, the fundamental condition for life is a certain “harmony” between the organism and the milieu in which it is placed. The proof of this is furnished at every turn by experience.   This being established, what will be the most general problem of the science of life? From the anatomical point of view, says Comte, all possible organisms, all parts whatever of each organism, and all the various states of each necessarily present a common basis of structure and of composition, from which the tissues, organs and apparatus have emerged by means of a progressive differentiation. In the same way, from the physiological point of view, all living beings, from the vegetable kingdom up to man, considered in all their actions and all the periods of their existence, necessarily possess a common basis of vital activity, whence the innumerable phenomena of nutrition, secretion, etc., proceed, by means of progressive differentiation. Now, from both these points of view, that which is similar in these cases, is more important than that which distinguishes them, since the more general phenomena govern those which are less so. We must therefore disengage the elementary physiological phenomenon and the anatomical structure which corresponds to it, we176 must determine their relation, and, with the help and confirmation of experience, we must deduce the increasingly more complex, physiological and anatomical, phenomena from it.159   This conception which, despite Comte’s reservation, still appears to be entirely saturated with the Cartesian spirit, leads him to the “most mathematical statement possible” of the biological problem. “Given the organ, or the organic modification, to find the function or the act, and vice versa.”160 There is nothing more in conformity with the general definition of science, which consists in substituting the knowledge of laws to that of facts, and rational prevision to empirical observation. Here, it is true, we have an “ideal scientific type,” from which biology, which has scarcely reached the positive state, is very far removed. But there is no science which does not fall short of its definition more or less. The use of this definition is already a help for a science, and provides a means for measuring its progress. III.   In part, or even entirely, biology is deprived of certain methodical processes which are utilised by the sciences which precede it. It cannot avail itself of calculation. Undoubtedly each of the elements which go to make up a physiological phenomenon varies according to a definite law. But the sum of these elements forms such a complex whole, that we shall never be able to express their relations in the terms of an equation. Further, the numbers which are relative to the phenomena of living bodies present continual and irregular variations, which do not allow us to establish the data of a mathematical calculation.161 Each living being has its individuality, its personal formula, its characteristic reactions, which prevent us from treating it as identical with177 the other beings of the same species. Each physiological or pathological “case” is distinct from any other case. That is why Comte distrusts statistics. In his judgment they are misleading in physiology, and fatal in medicine. In the same way, Claude Bernard will protest vigorously against averages.   Is the inductive method at least a convenient one to make use of in biology? Simple observation cannot lead us far in the study of such complex phenomena, of which many are not directly accessible to our senses or to our instruments. Experimenting is very difficult in biology, for nothing is easier than to disturb, to suspend, or even to bring about the entire cessation of the phenomena of life. But it is almost impossible to introduce an exactly determined perturbation, whether of kind, or, a fortiori, of degree. Indeed a modification of a single condition of the phenomenon almost at once affects the greater number of the other phenomena, by reason of their consensus. In principle, experimenting is not forbidden in biology. On the contrary it is of remarkable efficacy, but it is often impracticable.   Nevertheless, as we know, it is not man’s intervention in phenomena which constitutes experimenting properly so called. It consists, before all things, in the rational selection of cases, (natural or artificial, it matters little), which are most appropriate for bringing out the law of variation of the phenomenon under observation. Nature gives us such, for illnesses resemble experiments which we can follow through their entire course and to their termination. They are often difficult to interpret, on account of their extreme complexity, but less so, however, than the majority of the experiments which we bring about ourselves. For are they not more or less violent diseases, suddenly produced by our intervention, without our being able to foresee all their indirect and future consequences? It is pathological anatomy which led178 Bichat to his fine discoveries in histology and in physiology. And to pathology we must join teratology which is, as it were, its prolongation. Here again, nature supplies experiments which we should not know how to institute.162   Whatever may be the help which biology derives from these natural ways of experimenting, its progress could only be a very slow one, if it did not possess besides a powerful method for proceeding which is peculiar to it: comparison. It is true that every inductive operation implies comparison. We compare what we observe with other real and possible cases. Again we compare when we are experimenting. But, in the comparative method, properly so called, we do not limit ourselves to bringing two cases together. Comparison bears upon a long sequence of analogous cases, in which the subject is modified by a continual succession of almost insensible gradations.163   How would the general problems of biology receive a solution without this method? If we consider an organism by itself, the complication of functions and organs is inextricable in it. But, if we compare this organism with those which come nearest to it, and then with others which are near to them and so on, disengaging what they have in common, a simplification is produced. The accessory characteristics disappear by degrees, as we descend in the biological series, and, if we have set ourselves to study a certain function, we can finally determine its relation to its organ.   Although it belongs to biology, this method has its analogy in other sciences, and especially in mathematics. It appears to me, says Comte, to present a character similar to that of mathematical analysis, which brings forward, in each sequence of analogous cases “the fundamental portion which is common to all, which portion, before this abstract generalisation, was concealed beneath the secondary specialities of each isolated179 case.” The comparative method, in a word, is a method for analysing biological continuity. Whether it be a question of an anatomical disposition or of a physiological phenomenon “the methodical comparison of the regular sequence of the growing differences which relate to them will always present the surest and most efficacious means of throwing light upon even the ultimate elements of the proposed question.” We see that Comte had here his conception of the infinitesimal calculus in his mind. Better still, where terms are lacking in the organic series he does not hesitate to suppose them to re-establish continuity. He introduces intermediary “fictitious organisms” hypotheses which some day perhaps pal?ontology will turn into realities.   By means of this method, not only we shall know a far greater number of cases, but, what is of more importance, we shall know each one among them better, “as an inevitable consequence of their being drawn nearer together.” We assume, it is true, that all these various cases present a fundamental similarity accompanied by gradual modifications, which always follow a regular course. But this hypothesis as we have seen, is implied in the very definition of general biology.   The comparative method will then apply successively to the different parts of an organism, to the different ages of the same organism, and to the different organisms in the animal and vegetable series. It will even apply to embryonic life, Comte clearly formulates von Baer’s law, while making indispensable reservations. The primitive state of the highest organism, he says, must represent, from the anatomical and physiological point of view, the essential characteristics of the complete state which belongs to the more inferior organism, and so on successively “without our being able to find again the exact analogy of each of the principal terms of the inferior organic series in the sole analysis of the various phases of180 development of each superior organism.” This comparison, so to speak, allows us to realise in the same individual the growing complication of organs and of functions which characterises the whole biological hierarchy. Thus it is particularly “luminous.”164 Von Baer’s book had appeared in German in 1827. Had Comte known it, it is most probable that, according to his habit, he would have quoted it. IV.   In order to consider organisms in the regular sequence which allows of comparison, we must first have established the order in which they should be arranged. But, conversely, to establish this order, a knowledge of anatomy and physiology is indispensable. So between these two sciences on the one hand and “biotaxy” on the other there is a strict solidarity. The problem of classification is thus an essential part of general biology. In the natural classification sought after by science, the position assigned to each organism would suffice to define at once the whole of its anatomical and physiological nature, in relation to the organisms which precede and to those which follow.165 Any natural classification cannot, however, be anything but imperfect. Accustomed as we are to artificial classifications, which admit of absolute and immediate perfection, we are surprised that the same should not be the case in natural classification. But, if the latter is a real science, we must own that, here as elsewhere, we can only reach more or less distant approximations. The co-ordination of living species is a problem like the static or dynamic analysis of a determined organism. Like this analysis, it only allows of solutions which are approached rather than realised.166   How, in the first place, must we understand species? Between Cuvier and Lamarck, Comte sides with Cuvier,181 with this reservation, however, that “our ideas upon this question of capital importance are not yet properly fixed.” Two reasons especially incline him to admit the fixity of of species. Lamarck’s theory is not sufficiently proved: we nowhere see that the milieu exercises the almost boundless influence upon organisms which is attributed to it by Lamarck. Undoubtedly, within certain limits, the exercise induced by external circumstances tends to modify the primitive organisation. But this action of the milieu and this aptitude of the organism are certainly very limited. On the other hand, if we have a choice between the two hypotheses, the interest of science would prompt us to use this liberty in favour of Cuvier. The fixity of species guarantees that the series of organisms will always be composed of terms which are clearly distinct, separated by insuperable intervals. This “increases the degree of rational perfection of which the final establishment of this hierarchy is capable.”167 It is then under the influence of a purely formal motive that Comte’s preference is here decided. For he felt the strength and the import of Lamarck’s labours. Of the two celebrated antagonists, he said, Lamarck was unquestionably the one “who manifested the clearest and deepest sense of the true organic hierarchy.”168   Comte has even dealt with certain objections which do not go against Lamarck. Thus, we might think at first that, in his hypothesis, there is no real zoological series, since animal organisms would be essentially identical, their differences being henceforth attributed to the diverse and unequally prolonged influence of the external conditions. But, on looking into it more closely, we see, on the contrary, that this hypothesis only presents the series in a new aspect which would even render its existence still more evident. For the whole of the zoological series would then become, in fact as182 well as ideally, altogether analogous to the whole of the individual development, confined at least to its ascending period. It would then be conceived as continuous. “The progressive advance of the animal organism, which for us is only a convenient abstraction, would be converted into a natural law.”169   For the logical perfection of science, Comte prefers to regard species as fixed in the absence of contrary proofs. None the less Lamarck has stated a problem of the highest interest. Comte points out its importance. “The rational theory of the necessary action of the various milieux on the different organisms has still almost entirely to be formulated. Such an order of research, although greatly neglected, constitutes one of the finest subjects which the present condition of biology can present.” By this means, he adds, we might obtain a theory for the perfecting of living species even including mankind.170 V.   Comte’s anatomical and physiological philosophy is naturally allied to the science of his time. It is especially connected with the labours of Bichat and of de Blainville. Here again he endeavours to state the problems in the most general form possible. Anatomy should begin by the study of the tissues, to ascend afterwards to the association of several tissues, that is to say, to the organs, and to the associations of several organs, that is to say, to systems. But analysis must not be concerned with the tissue itself. To attempt the passage from this notion to that of the molecule, is to allow the organic to enter into the inorganic philosophy. In biology, the tissue corresponds to what the molecule is in physics. Such, at least, is the doctrine of the Cours de philosophie positive.183 Later on, instructed by Schwann’s works, Comte admits in the Politique positive that the anatomical element is the cell.   Be it tissue or cell, there must be a fundamental anatomical element. The simultaneous existence of several elements independent of one another would greatly mar “the admirable unity of the organic world,” and consequently the perfection of biological science. Life is always essentially the same. To this dynamic consideration, there must correspond, in the static order, that of a common basis invariable in its primordial organisation, successively producing, by deeper and deeper modifications, the various special anatomical elements.   Similarly, physiology will not be entirely organised until it studies functions (at least the organic functions), throughout the whole chain of living beings, from the vegetable kingdom up to man. This conception of a general physiology leads Comte to dwell, as Claude Bernard will later on, upon the phenomena of life which are common to plants and to animals. Some are better studied in plants and others in animals. But, whether it be animal or vegetable every organism always presents two fundamental functions: 1. the absorption of nutritious materials borrowed from the milieu (the assimilation of these materials and finally nutrition); 2. the rejection of unassimilated materials. However, plants are the only organised beings which live directly upon the inorganic milieu.171 Comte was ignorant of the physiology of fungi.   Comte unreservedly adopts the distinction established by Bichat between the functions of organic life and those of animal life. In the first place he concludes from this, in virtue of the correlation of the dynamic to the static point of view, that distinct tissues correspond to these distinct functions. Then, he goes more deeply into the difference between the two kinds of functions. Strictly speaking, the phenomena of organic life only constitute a special order of184 composition and of decomposition. They come very near to chemistry, and may serve as a transition between the inorganic world and the world of life.172 On the contrary, the phenomena of animal life (irritability, sensibility), offer no analogy with the phenomena of the inorganic world. We might almost believe, according to Comte, that the separation is established not between the chemical and biological phenomena, but between organic and animal life, the phenomena of the former reducing themselves to physico-chemical phenomena, and those of the latter presenting entirely different characteristics. Such is not, however, Comte’s thought. Undoubtedly, considered one by one, the phenomena of organic life (absorption, circulation, exhalation, etc.) are indeed physico-chemical phenomena. But what renders their biological character irreducible is that it is impossible to consider them separately: in order to understand them we must first look at them from the point of view of the whole, and appeal to the organic consensus, in a word, to what Claude Bernard, will call l’idée directrice.   In the study of organic functions we shall begin by the lower extremity in the series of living beings, that is to say by the most rudimentary forms of the vegetable kingdom, for it is here that we shall grasp the phenomena in their simplest form. Then we shall follow their growing complexity. For the animal functions, on the contrary, it is expedient to begin by man, “the only being in which such an order of phenomena is ever immediately intelligible.” From this point of view man is pre-eminently the biological unity. As soon as it is a question of the characteristics of animality, we must begin with man and see how they descend by degrees, rather than start from the sponge, and look for their mode of development. Man’s animal life helps us to understand that of the sponge; but the reverse is not true.173 Moreover, the phenomena of or185ganic life, being the most general, are also the most fundamental. The functions of animal life are first useful for the needs of organic life, by perfecting it. It is in man alone that the vegetative life is subordinate to the life of relation: and even for that he must have reached a high degree of civilisation.174 VI.   It is not surprising that biology, even more than physics and chemistry, preserves the metaphysical spirit. Such, for instance, is the hypothesis of spontaneous generation. Positive philosophy recognizes that each living being always emanates from another similar being. This is not established a priori, but is the result of an “immense induction.”175 Omne vivum ex vivo. Efforts to explain how the generating tissue should itself be formed by kinds of organic monads, (an allusion to certain theories arising out of Schelling’s philosophy) can only fail. We should never know how to connect the organic with the inorganic world except through the fundamental laws belonging to the general phenomena which are common to them both. Positive speculations in anatomy and in physiology form a limited system, within which we must establish the most perfect unity, but which must ever remain separated from the whole of inorganic theories.176 We see clearly, it is true, that there is no matter which is of itself living. Life is not peculiar to certain substances which are organised in a certain manner. It never belongs to them for more than a time: every organism of which the molecules are not renewed is dissolved. But “we can no more explain this instability than this speciality.”177   In the same way we see that in living bodies the nutritive186 functions are the basis of the others; but there is no contradiction in “dreaming” of thought and sociability in beings whose substance would remain unalterable. From this point of view spiritualism is not less admissible than materialism, in so much as death does not seem to be a necessary consequence of life. This again is an idea which is common to Descartes and to Comte. They both conceive an organism in which the play of functions should not cease of itself. The theory of death, says Comte, although it is founded upon that of life, is entirely distinct from it.178   If biology still often hesitates in the statement of its problems and in the choice of its hypotheses, it is in a great measure due to the two opposite tendencies between which it oscillated in the last century. On the one hand, Boerhaave, and the school of physiology which is more or less directly connected with Descartes, sought a mechanical explanation of biological phenomena, and tended to reduce biology to physics and chemistry. On the other hand, Stahl in Germany, and the vitalist school of Montpellier in France, appealed to metaphysical principles and to unverifiable hypotheses. Being thus swayed from one extremity to another, biology only escaped the “oppression” of the inorganic sciences to involve itself in conceptions which were scarcely scientific.179 It is only at the end of the XVIII. Century, with Haller, Gall and Bichat, that it finds its equilibrium, takes possession of its method, and at last enters into its positive phase.   By its lower extremity it is contiguous to inorganic science (the physico-chemical phenomena of vegetative life). By its higher extremity, (intellectual functions), it reaches to the final science, or sociology. But the adherence is far from being as close in one case as in the other. At the moment when we pass from the inorganic world to the world of living beings, according to positive philosophy, there is a sudden187 “enrichment of the real.” The transition is very marked. The domain of biology is not so sharply separated from that of sociology. For the higher biological functions, the intellectual functions, cannot be analysed from the point of view of the individual, at least in man, but only from the point of view of the species. We must then, while preserving the distinction between the two sciences, admit a kind of inter-relation between them. Undoubtedly sociology could not be founded so long as biology had not made decisive progress. But, conversely, sociology once founded alone completes the positive study of the highest biological functions.   Certainly, biology has not been less transformed than chemistry during the last sixty years, and the state in which we see it to-day differs singularly from that in which Comte knew it. It has been developed and differentiated far beyond what he could foresee. None the less he conceived some of its principles with remarkable power. He had a precise idea of that which could constitute a general biology that is, a single physiology and anatomy for the whole of living beings. He knew the fecundity of the comparative method, and he pointed out its analogy with the method of analysis in mathematics. Finally, although he refused to adopt the transformist hypothesis, he had understood the importance of Lamarck’s work.