Development

of Statical

biology.

CHAPTER II.

ANATOMICAL PHILOSOPHY.

T

T was during the second half of the last century that Daubenton and Vicq-d'Azyr achieved the extension of the statical study of living bodies to the whole of known organisms; and the lectures and writings of Cuvier carried on, and spread abroad, the regenerating influence of this great view. But, indispensable as was this conception to the development of anatomical science, it could not complete the character of statical biology without the aid and addition of Bichat's grand idea of the general decomposition of the organism into its various elementary tissues; the high philosophical importance of which appears to me not yet to be worthily appreciated.

The natural development of comparative anatomy would, no doubt, have disclosed this analysis to us sooner or later: but how slow the process would have been we may judge by what we see of the reluctance of comparative anatomists to abandon the exclusive study of systems of organs while unable to deny the preponderant importance of the study of the tissues. Of all changes, those which relate to method are the most difficult of accomplishment; and perhaps there is no example of their resulting spontaneously from a regular advance under the old methods, without a direct impulsion from a new original conception, energetic enough to work a revolution in the system of study. Biology must, from its great complexity, be more dependent on such a necessity than any other science.

Though zoological analysis furnishes the best means of separating the various organic tissues, and especially of giving precision to the true philosophical sense of this Process of great notion, pathological analysis offered a discovery of more direct and rapid way to suggest the the tissues. first idea of such a decomposition, even re

PROCESS OF DISCOVERY OF THE TISSUES.

49

garding the human organism alone. When pathological anatomy had been once founded by Morgagni, it was evident that in the best-marked maladies no organ is ever entirely diseased, and that the alterations are usually confined to some of its constituent parts, while the others preserve their normal condition. In no other way could the distinction of the elementary tissues have been so clearly established. By the co-existence in one organ of sound and impaired tissues, and, again, by different organs being affected by similar maladies, in virtue of the disease of a common tissue, the analysis of the chief anatomical elements was spontaneously indicated, at the same time that the study of the tissues was shown to be more important than that of the organs. It is not consistent with my objects to go further into this: but it was necessary to show that we owe to pathological analysis the perception of this essential truth. It was Pinel who suggested it to Bichat, by his happy innovation of studying at once all the diseases proper to the different mucous membranes. Bichat then, while knowing nothing of the study of the organic hierarchy, carried off from the students of comparative anatomy the honour of discovering the primitive idea which is most indispensable of all to the general advancement of anatomical philosophy. His achievement consisted in rationally connecting with the normal condition a notion derived from the pathological condition, in virtue probably of the natural reflection that if the different tissues of the same organ could each be separately diseased in its own way, they must have, in their healthy condition, distinct modes of existence, of which the life of the organ is really composed. This principle was entirely overlooked before Bichat published the treatise in which he established the most satisfactory à posteriori development of it: and it is now placed beyond all question. The only matter of regret is that, in creating a wholly new aspect of anatomical science, Bichat bid not better mark its spirit by the title he gave it. If he had called it abstract or elementary instead of general anatomy, he would have indicated its philosophical function, and its relation to other anatomical points of view.

The anatomical philosophy began to assume its definitive

Combination character from the very recent time when with Compathe human mind learned to combine the rative anatwo great primitive ideas of the organic hiertomy. archy, and of Bichat's discovery, which applies the universal conception to the statical study of living bodies. These combined ideas are necessarily the subject of our present examination. Putting aside the irrational distinctions, still too common among biologists, of many different kinds of anatomy, we must here recognize only one scientific anatomy, chiefly characterized by the philosophical combination of the comparative method with the fundamental notion of the decomposition of the organs into tissues. It is apparently strange that, after Bichat's discovery, comparative anatomists, with Cuvier at their head, should have persisted in studying organic apparatus in its complex state, instead of beginning with the investigation of the tissues, pursuing the analysis of the laws of their combinations into organs, and ending with the grouping of those organs into apparatus, properly so called: but not even Cuvier's great name can now prevent the application of the comparative method to the analysis of tissues, throughout the whole biological hierarchy. The work, though at present neither energetically nor profoundly pursued, is begun, and will reform the habitual direction of anatomical speculation.

Elements and
Products.

Bichat's studies related to Man alone; and his method of comparison bore only upon the simplest and most restricted cases of all; the comparison of parts and that of ages. His principle must, therefore, necessarily undergo some transformations, to fit it for a more extensive application. The most important of these improvements, especially in a logical view, appears to me to consist in the great distinction introduced by M. de Blainville between the true anatomical elements and the simple products of the organism, which Bichat had confounded. We saw before the importance of this distinction in the chemical study of organic substances: and we meet it again now, face to face, as an anatomical conception.

We have seen that life, reduced to the simplest and most general notion of it, is characterized by the double con

ELEMENTS AND PRODUCTS.

51

tinuous motion of absorption and exhalation, owing to the reciprocal action of the organism and its environment, and adapted to sustain during a certain time, and within certain limits of variation, the integrity of the organization. It results from this that, at every instant of its existence, every living body must present, in its structure and composition, two very different orders of principles: absorbed matters in a state of assimilation, and exhaled matters in a state of separation. This is the ground of the great anatomical distinction between organic elements and organic products. The absorbed matters, once completely assimilated, constitute the whole of the real materials of the organism. The exhaled substances, whether solid or fluid, become, from the time of their separation, foreign to the organism, in which they cannot generally remain long without danger. Regarded in a solid state, the true anatomical elements are always necessarily continuous in tissue with the whole of the organism: and again, the fluid elements, whether stagnant or circulating, remain in the depths of the general tissue, from which they are equally inseparable: whereas the products are only deposited, for a longer or shorter time, on the exterior or interior surface of the organism. The differences are not less characteristic, in a dynamical view. The true elements alone must be regarded as really living: they alone participate in the double vital motion: and they alone grow or decrease by absorption or exhalation. Even before they are finally excreted, the products are already essentially dead substances, exhibiting the same conditions that they would manifest anywhere else, under similar molecular influences.

The separation of the elements from the products is not always easy to effect when, as frequently happens, they combine in the same anatomical arrangement to concur in the same function. All products are not, like sweat, urine, etc., destined to be expelled without further use in the organic economy. Several others, as saliva, the gastric fluid, bile, etc., act as exterior substances, and in virtue of their chemical composition in preparing for the assimilation of the organic materials. It is difficult to fix the precise moment when these bodies cease to be products and become elements;-the moment, that is, when they pass from the

It

inorganic to the organic state,-from death to life. But these difficulties arise from the imperfection of our analysis, and not from any uncertainty in the principle of separation. may be observed however that there are circumstances in which products, and particularly among the solids, are closely united to true anatomical elements in the structure of certain apparatus, to which they supply essential means of improvement. Such are, for instance, the greater number of epidermic productions, the hair, and eminently the teeth. But even in this case, a sufficiently delicate dissection, and a careful analysis of the whole of the function will enable us to ascertain, with entire precision, how much is organic and how much inorganic in the proposed structure. Such an investigation was not prepared for when Bichat confounded the teeth with the bones, and concluded the epidermis and the hair to be tissues, of a piece with the cutaneous tissue; but the rectification which ensued was all-important, as enabling us to define the idea of tissue or anatomical element, which is the preferable term. It was through comparative anatomy that the rectification took place; for the study of the biological series showed that the inorganic parts which in Man appear inseparable from the essential apparatus are in fact only simple means of advancement, gradually introduced at assignable stages of the ascending biological series.

If we assert that in the order of purely anatomical speculations, the study of products must be secondary to that of elements, it will not be supposed that we undervalue the study of products. This study is of extreme importance in physiology, whose principal phenomena would be radically unintelligible without it; and without it pathological knowledge must come to a stand. As results, they indicate organic alterations; and as modifiers, they exhibit the origin of a great number of those alterations. In fact, the knowledge of them is much promoted by their separation from the anatomical elements, which withdraw the attention of biologists from the real claims of the whole class of products.

The consideration of products being once dismissed to its proper place, anatomical analysis has assumed its true character of completeness and clearness. Thus we may