( Originally Published 1913 )
HAVING indicated, though briefly, the most important generalities with respect to the object, scope, and Method of the study of living beings, we may now glance at Comte's division of the subject into its statical and dynamical elements,—Anatomy, comparative and descriptive, and Physiology.
Anatomy was enveloped in inextricable confusion so long as it proceeded only with a view to organs, and groups of organs. Bichat, by his grand philosophical device of decomposing the organism into its various elementary tissues, rendered Anatomy the greatest of services. For although a profound investigation of the whole animal kingdom, proceeding on the ascensional Method from the lowest upwards to man, will reveal to us the various tissues successively emerging into special distinctness as the diverse functions become more and more pronounced ; nevertheless, this discovery would have necessarily been much slower, had it not been for Bichat's philosophic innovation,—as indeed may be seen in the fact of Cuvier, although coming after Bichat, having never familiarized his mind with the importance of this view, but continuing to occupy himself with the organs and groups of organs, hoping there to read the answer to his questions. The organs themselves are made up of tissues, and therefore the priority of the tissues is beyond dispute.
This, then, is the order laid down by Comte in conformity with his method of proceeding from the general to the special, the simple to the complex. We must commence with the study of the tissues, and thence proceed to the analysis of the laws of their combination into organs, and finally, to the consideration of the grouping of those organs into systems.
A slight rectification of this order is necessary, and a disciple of Comte's—Dr. Sêgond—in his Systématisation de la Biologie, has suggested it. He says we should precede the investigation of the tissues by that of the proximate principles,—viz., the phosphates, fats,, salts, albumen, &c. These, combined with the " anatomic elements" (cells, fibres, tubes), constitute the Organic Elements, that is to say, the elementary constituents of organic matter. For a thorough investigation of this subject, and at the same time for the most exhaustive application of the positive Method in elementary Anatomy, the philosophic biologist is referred to the large work of Drs. Robin and Verdeil—Traité de Chimie Anatomique.
That the starting point of all the tissues is the Protein of Mulder, no organic chemist now doubts, although the existence of this protein, which Mulder fancied he had discovered, is generally given up, But although it is probable that no such basic combination of the four organogens does actually exist, the conception—as a philosophic artifice—is too useful to be dis-regarded ; and anatomists speak, therefore, of protein as a brief expression for the four organogens. In fact, this conception is only an application to organic bodies of the conception of Compound Radicals and we may employ it as we employ the conception of radicals in inorganic chemistry, without necessarily believing in their objective existence.
We trace the transformation of this protein into Albumen, Fibrine, and Caseine, by the additions of certain proportions of sulphur, or phosphorus, or of both, as a preliminary to our investigating the transformation of the cellular tissue into the other tissues. Herein we see the intimate relation of Biology with Chemistry. And, while on this point, let us note the chemical analysis of these elements given by Mulder.
Having settled the order to be—Proximate principles, Elements, Tissues, Organs, and Groups of Organs or Systems—we have to trace the transformation of all the tissues from one, and their classification according to their true general relations.
After pointing out the value of De Blainville's distinction between the organic elements and organic products, Comte opens the question of the vitality of organic fluids.
" A glance at the ensemble of the organic world shows us clearly that every living body is continually formed out of a certain combination of solids and fluids, of which the proportions vary according to the different species. The very definition of life presupposes the necessary harmony of these two constituent principles. For this twofold internal movement of composition and decomposition which essentially characterises life, cannot be conceived in a system altogether solid. On the other hand, independently of the impossibility of a purely liquid mass existing, without being contained by some solid envelope; it is clear that such a mass could not be or. ganized, and life, properly so called, becomes unintelligible in such a mass. If these two parent ideas of life and organization were not necessarily co-relative and, consequently, inseparable, one might conceive that life essentially belonged to the fluids, and organization to the solids. Indeed, the comparative examination of the principal types seems to confirm as a general rule, that vital activity augments essentially in proportion as the fluids predominate in the organism, while, on the contrary, the . increasing preponderance of the solids determines a greater persistence of the vital state. These reflections prove that the celebrated controversy on the vitality of fluids rests on a vicious position of the problem altogether, since the necessary co-relation between fluids and solids excludes, as equally irrational, either the absolute humorism or absolute solidism.
" Nevertheless, in considering the various proximate principles of the organic fluids, there is one series of positive researches to be made respecting the veritable vitality of the organic fluids. For example, the blood being formed principally of water, it would be absurd to suppose this inert vehicle as participating in the incontestable vitality of the blood ; but wherein lies this vitality ? The microscopic anatomy of our day (1838) has answered this question by making the red globules the seat of vitality, they alone being organized. But this solution, precious though it be, can only as yet be considered as a simple sketch of the truth. For it is admitted that these globules, though always of determinate form, become narrower and narrower as the arterial blood passes into the inferior vessels, that is to say, in advancing towards the seat of its incorporation with the tissues ; and finally, that at the precise instant of definitive assimilation there is a complete liquefaction of the globules. Now this seems in open contradiction with the hypothesis, since here the blood would cease to be vital at the moment of its accomplishing its greatest act of vitality."
The net result of this examination of the vitality of the fluids, together with some other observations for which there is no space here, is, that Comte would begin the static investigation with the solids, as best representing the idea of organization, and from the solids pass to the fluids.
Thus we arrive once more at the tissues as the anatomical starting-point. And here, as elsewhere, the immense importance of Comparison stands prominent, the earlier phases of human development being too rapid and too removed from observation for Anatomy to get its clue there ; only in the biological hierarchy, embracing all organized beings, can we look for decisive indications. Following this Comparative Method we find that the cellular tissue is the primary and essential basis of every organism, being the only one universally present. All the various tissues which in man seem so distinct, successively lose their characteristic attributes as we descend the scale of organisms, and always tend to lose their identity in the cellular tissue, which, as we know, remains the sole basis of the vegetable world, and also of the lowest forms of the animal world.
" We may remark here," says Comte, " how the nature of such an elementary organization is in philosophic harmony with that which constitutes the necessary basis of life in general, reduced to its abstract terms. For under whatever form we conceive the cellular tissue, it is eminently fitted, by its structure, to that absorption and exhalation which form the two essential parts of the great vital phenomenon. At the lowest stage of the animal hierarchy, the living organism, placed in an in-variable medium, is really limited to absorption and exhalation by its two surfaces, between which circulate the fluids destined to be assimilated and those resulting from disassimilation. For a function so simple the simple cell is sufficient."
Having ascertained that the cellular tissue is the primordial tissue successively modified into other tissues, we have to trace the order of succession; and here Comparative Anatomy again comes to our aid, and guides us by this simple luminous principle—that the secondary tissues are to be regarded as more widely separated from the primary tissue, just in proportion as their first appearance takes place in the more special and more complex organisms. For example, the nervous tissue is totally absent from all vegetable organisms, and is undiscoverable in the lowest forms of animal organisms, by Owen named, in consequence, Acrita. Again, in the muscular tissue there are two distinct varieties, the striped and unstriped fibres ; the former peculiar to the voluntary or more complex muscles, the latter to the involuntary muscles. But the latest researches show that as we descend the animal hierarchy we find the distinctive characters of these fibres gradually merging together. The transverse stripes grow irregular instead of parallel; the fibres possess them only near the centre, where the development is greatest, and the contractile energy most active.
The modifications which the cellular tissue undergoes may, in general, be divided into two classes : the most ordinary and least profound are those of simple structure ; the other, more profound and more special, affect the very composition of the tissue itself.
" The most direct and general of these transformations generates the dermal tissue, properly so called, which constitutes the basis of the organic envelope, external and internal. Here the modification is reduced to a simple condensation, varying according as the surface has to be more absorbent or exhalant. This trans-formation, simple as it is, is not rigorously universal ; we must ascend to a certain stage of the biological scale before perceiving it distinctly. Not only in the majority of the lower animals is there no essential difference between the external and internal surfaces, which can, as is well known, mutually supply each other's places ; but if we descend a little lower, we are unable to discern any anatomical distinction between the envelope and the ensemble of the organism, which is wholly cellular.
" An increasing condensation, more or less equally distributed, of this cellular tissue, determines-in starting from the dermal tissue, and in a higher stage of the organic series—three distinct but inseparable tissues, destined to play an important part in the animal economy, as the protective envelopes of the nervous system, and as auxiliaries to the locomotive apparatus. These are the fibrous, cartilaginous, and osseous tissues—the fundamental analogy of which is evident, and has led M. Laurent, in his scheme of systematic nomenclature, to fix this analogy by the application of the general term sclerous tissue to the three. The propriety of this is the more evident, because, in reality, the different degrees of consolidation result from the deposit of a heterogeneous substance, either organic or inorganic, in the network of the cellular tissue, and the extraction of this substance leaves no doubt whatever as to the nature of the tissue. When, on the contrary, by a final condensation, the primary tissue becomes more compact, without encrusting itself with any foreign substance, then we pass to a new modification, where impermeability becomes compatible with elasticity, which characterizes the serous tissue, the destination of which is to interpose itself between the various organs, and above all to contain the fluids of the body."
These are the tissues necessary to Organic life ; and as Animal life is so markedly distinguished from Organic life, we may be prepared for some equivalent distinction in the modification of the tissues proper to Animal life,—viz., the muscular tissue and the nervous tissue. In each case the modification is characterized by the anatomical combination of the fundamental cellular tissue with a special organic element, which, of course, affects its whole composition. In the case of the muscular tissue, the organic element is that well known as fibrine (the analysis of which has already been given), and in the case of nervous tissue, the element is that named by De Blainville neurine. The modification now spoken of is too great for us in the present state of science to describe with precision ; but no philosophical anatomist will doubt the reality of the process, unless he prefer the supposition of three primitive tissues,—cellular, muscular, and nervous,—a supposition which would disturb the whole unity of Nature.
This, then, is the object of Philosophical Anatomy to reduce all the tissues to one primordial elementary tissue, from which they are developed by modifications more and more special and profound, first of structure and then of composition.
Comte energetically raises his voice against that tendency among modern German anatomists to quit the real positive point of view for some more inaccessible and chimerical position, which, if attainable, would only remove the subject still farther, and in no case explain it. Instead of contenting themselves with the reduction of all the tissues to one, they endeavour to reduce that one to an assemblage of organic monads, which are the primordial elements of all living beings. This is contrary to all sound Biology. In the science of life what have we to study but the phenomena of organized beings ? To go beyond the organism is to step beyond the limits of the science. That the differences between the inorganic and organic worlds are phenomenal, and in no wise nomenal, I have endeavoured to prove in the sections on Organic Chemistry; but these phenomenal differences are in philosophy essential, and whoever confounds them sins against fundamental principles.
In one sense it is true that Life is everywhere ; but in the restricted sense in which Biology considers Vitality -viz., as the co-relation of two inseparable ideas, Life and Organization—it is obviously absurd to suppose Life as resident in molecules. In what could the organization or the life of a monad consist ? " That the philosophy of inorganic matter should conceive all bodies as composed of indivisible molecules, is rational enough, being perfectly conformable to the nature of the phenomena, which, constituting the general basis of all material existence, must necessarily belong to the smallest particles. But, on the contrary, this biological heresy is only an absurd imitation of that conception, and, reduced to plain terms, it supposes all animals to be composed of animalcules. Even admitting this supposition, the elementary animalcules become more incomprehensible than the animals, not to mention the gratuitous difficulty introduced of their association into one animal.
In thus objecting to the doctrine of monads, Comte must not be supposed to allude to the cell-doctrine, which, at the time he wrote, did not exist. He merely wishes to keep the unity of each organization distinct. "Any and every organism constitutes by its nature an indivisible unit; it is true that by an intellectual artifice we can de-compose that unit the better to understand it; but the last term of that abstract decomposition consists in the idea of tissue, beyond which (if we combine with it the idea of elements) nothing can anatomically exist, because beyond it there can be no organization. The idea of tissue is to the organic world what the idea of molecule is to the inorganic."
I know not if the " general reader" has been able to follow this abstract statement of the fundamental prin.. ciples of philosophical Anatomy, but he need only open any of the works specially devoted to this science, and he will perceive at once the simplicity, profundity, and luminousness of the principles Comte has laid down.