1847.] Pathological Epigeneses. 435 mensely thickened peritoneum, exhibited scarcely any thing else than an infinite number of minute wavy fibres, like those of areolar tissue, and without a trace of the cells seen in true scirrhus. As several notices of the Blood have recently appeared in this Journal, we pass by the Chapter on the Pathological relations of that fluid, though it will well repay a careful perusal. The larger portion of the present volume is occupied with what Dr. Day terms "Pathological Epigeneses." The original expression (Neubildungen) signifies literally new formations." Although neither of these names is free from objection, we think, on the whole, that employed in the translation is the best of the two. It expresses, for example, more truly the relations of fibrous and fatty tumours to the normal structures; these can hardly be regarded as entirely new productions, inasmuch as they resemble the natural tissues after which they are named, both when seen by the eye and when examined by the microscope. But the fact is that the error lies with the author, who in his zeal for philosophic generalization, has placed in one category a number of essentially different morbid productions pus, fibrous, fatty, and encysted tumours-tubercle, scirrhus, and encephaloid-and even unorganized deposits, such as urinary and biliary calculi. It is clear that the laws regulating many of these growths and concretions, are so totally distinct, that no benefit can accrue by regarding them, even . remotely, from the same point of view. After dividing pathological epigeneses into two groups, the organized and unorganized, Dr. Vogel observes that, like every thing else in Nature, there must be a matter from which they may be produced. To this, which may either be fluid or solid, he applies the general terms plasma or formative maller. "A plasma may act as formative material either for organized or unorganized products, or for both at the same time. The plasma for unorganized formations, which is usually an aqueous solution, from which deposits are produced or crystals formed in accordance with chemical laws, we shall name a mother-liquid; the matter giving rise to organized formations which are chiefly produced by the formation of cells, we shall term a cytoblastema, or, for brevity, a blastema; and lastly, a plasma, from which organized and unorganized products are developed, will be designated as a mixed plusma."-P. 101. As regards the plasma of organized pathological formations, or blastema, it must always be amorphous, that is to say, it must neither be crystalline nor have a definite organic form. It is evident that, if this principle can be firmly established, the old idea, namely, that a tissue may be directly converted into a pathological formation, must be overturned. This, for general pathology, is therefore a most important question, and is ably discussed in the work before us. We need scarcely remind our readers that the tendency in all sciences in proportion as they advance, is to refer their varied phenomena to a few general laws. In the particular instance of organization, this has been strikingly illustrated in late years; and one of the most fundamental of these generalities is, that whatever may be the ultimate form of organized matter, whether normal or diseased, it has apparently but one origin, namely, fibrin, which is therefore to be regarded as the plastic element in all nutritive processes. With respect to healthy nutrition, this position seems to be satisfactorily proved, at least there is at present no known example of albumen, fat, or other proximate principle, becoming directly organized. It may be thought, indeed, and this is the opinion of Vogel, that, in the case of the egg, the prototype of all formative fluids, and which up to this time is not known to contain fibrin, there is an exception to this rule. But there is good reason to believe that the received opinions upon this subject are erroneous; for we ascertained some few years since that the formative matter in the egg of the fowl lying immediately beneath the germinal membrane, and which is a compound formed by the admixture of the white and the yelk, differs from both those albuminous substances, by being perfectly liquid and not coagulable by the ordinary tests for albumen. This fluid matter is probably fibrin, and when it is recollected how similar is the chemical constitution of albumen and fibrin, and how readily the former is converted into the latter, of which the best example is furnished in the changes taking place in the chyle as it traverses the lacteal absorbents, there is no difficulty in conceiving of an analogous action going on in incubation. Whatever doubts may yet remain upon the point just considered, there can scarcely be any with respect to the principle that fibrin is essential to all morbid products: upon this question the author speaks most decidedly. After showing that non-azotized substances, such as fat, salts, &c., cannot act as blastema for organized formations, he proceeds to observe : "Hence there remain, as the actual and potential constituents of the blastema, only the protein-compounds; although these are never found alone in the body, being always associated with the above-named substances. Further, all these protein-compounds are not susceptible of development. Fluids which merely contain dissolved albumen and the above substances never appear to act as cytoblastemata. In the common dropsical effusions, which are always rich in albumen, we never observe any organized products, unless fibrin be also present; this is at least the result of my own observations, which have been very numerous, and I am not acquainted with a single exception to the law. Moreover, fluids in which casein is the only protein-compound, cannot, as far as observation has yet shown us, act as blastemata. In the milk, for instance, as long as it contains merely casein, we never observe any pathological formations, for the granular bodies belong to the normal process of development of the milk; as soon, however, as any fibrin is present, morbid products, such as pus-corpuscles, may be formed in it. On the other hand, in all fluids which we regard as cytoblastemata for morbid products, fibrin has always been found: hence we must regard it as the necessary and apparently the most essential ingredient in the cytoblastema. This law respecting the necessity for the occurrence of fibrin in the cytoblastemata of morbid products, I have seen to hold good in several hundred cases, without a single exception."-P. 107. Having determined the first great principle connected with organized epigeneses, namely, that they all spring from fibrin, the organizable matter par eminence, Dr. Vogel enters upon another of these fundamental questions which lie at the bottom of all sound pathology-on what is the development of the cytoblastema dependant? He sets out with an assertion, for which we think there is no sufficient ground, to the effect that chemical action cannot be the efficient cause; the arguments for this opinion are, however, derived more from our ignorance than from our knowledge, and are, for this reason, not very satisfactory. A careful consideration of the phenomena connected with the coagulation of fibrin, 1847.] Development of Cytoblastema. 437 and of the first and essential steps in the process of its organization, induces us to express an opinion that the changes perceived are rather of a physical than of a vital character. They are connected, for example, with an alteration in the form of matter, the liquid lymph becoming solid and fibrillated, phenomena indicating, like the conversion of water into ice, or the formation of crystals from a saline solution, a subtle molecular action. The production of the peculiar corpuscles observed in coagulated fibrin, and evidently one of the earliest and most important steps in its organization, may be explained in a similar way. The predominating influence of chemical forces in the nutritive process, evinced especially in digestion, respiration, and secretion, of itself renders it a reasonable proposition, that the same agencies are operative in the whole of what is called the organic life. Dismissing the question relating to the nature of the forces employed, we proceed with the author to inquire where they operate, and, to obtain what the Germans call a standpunkt, or starting-point, two hypotheses may be assumed: "There are two different causes which may be supposed to affect the transition of the blastema in development; firstly, the cause may be grounded on the nature of the cytoblastema, and the formation may be developed with the same necessity which, under favourable conditions, compels the separation of certain crystals from their mother-liquid; or secondly, the transition in the development may be dependant on external conditions, independent of the cytoblastema, as for instance, on the influence of the surrounding parts of the body, &c."-P. 110. In order to ascertain which of these hypotheses is deserving of preference, it is necessary" to distinguish between the capacity of the cytoblastema in the progress of development (potentia) and the actual transition (actus)." With respect to the capacity, Vogel justly remarks, no one will deny that it essentially belongs to the cytoblastema; for, if it depended on external influences, then would every substance placed in similar relations undergo the same process of development, an assumption entirely at variance with experience. The author concludes, as regards the "actual transition," in the instance of morbid products, that, as a rule, it can only be effected by the agency of the surrounding parts. He admits, it is true, some isolated exceptions, such as that pathological elements, especially pus-globules, can be produced without the contact of organized tissues. The general inference, as maintained in the work before us, is then that although the capacity for organization is inherent, in every instance, in the cytoblastema, the act itself is dependant upon the surrounding tissues, which are further believed by Dr. Vogel to have the power of converting the new matter into their own texture, although the nature of the blastema is not a matter of indifference, more particularly, as it would appear, in those diseases in which the morbid product is altogether different from the surrounding parts, as in scirrhus, encephaloid, &c. The views of the author on this interesting question are thus set forth: "In the process of regeneration and in hypertrophy, where the influence of the cytoblastema on the nature of the development is at its minimum, the development itself appears to be entirely dependant on the normal histological elements between which the blastema is effused. Thus, in regeneration and hypertrophy, the blastema between areolar tissue, becomes areolar tissue; in the vicinity of bone, it becomes cartilage and bone; between muscular fibres, it is converted into similar tissue at the extremities of divided nervous fibrils, it forms nervous substance, &c. The circumstance that these and no other structures are formed, cannot in these instances be dependant on the blastemata, which, as far as chemical analysis goes, seem to be the same; and it is entirely the influence of the surrounding parts that modifies the character of the development. Here, then, if we may be allowed the expression, we are entering the department of solid pathology. "But it may be further asked: it being granted that, in the above cases, the nature of the development is essentially dependant on parts of the body already formed, what is the case with those pathological epigeneses in which the resulting morbid product is perfectly different from the surrounding parts, as in scirrhus, encephaloid, tubercle or pus? Is not the abnormal character of the product dependant on a peculiar pre-existing blastema, so that there is always one kind of blastema for scirrhus, another for encephaloid, and so on? "We are yet hardly in a condition to answer this question satisfactorily. It is quite possible that the elements of the peculiar structures of scirrhus and encephaloid may be traced to the blastemata from which they spring, and that, in accordance with the views of the humoral pathologists, the pseudo-plasma may be dependant on an abnormal chemical composition of the blood. Another explanation may be attempted which equally elucidates the appearance of these peculiar morbid products, namely, that the peculiarity of the epigenesis is not dependant on any property of the blastema, but on changes in the properties of the tissues influencing the blastema; and thus the explanation of these phenomena is again transferred from the department of humoral to that of solid pathology, or, since in many cases these changes are dependant on a change in the nervous influence, to that of nervous pathology. It is, however, in the highest degree probable, that in the majority of cases neither the one nor the other of these views alone is strictly correct, that for the most part changes in the cytoblastema and changes in the physiological properties of the tissues are conjointly at work in producing an abnormal epigenesis."-P. 114. In supporting his doctrine, Dr. Vogel takes as a basis the process of natural development as it is witnessed in the egg of the bird. Although entirely agreeing in the necessity of this mode of procedure, we cannot coincide with this distinguished pathologist in some of his deductions. Being satisfied that, in all speculations of this character, the ultimate facts of organization can only be discovered by setting off with the fixed assurance that simplicity and unity pervade all the works of Nature, we cannot admit that there is any essential difference, which the author affirms there is, between the nutrition of the perfect organism and the formation of the new being in the egg. In the latter case, it is certain and admitted, that the cytoblastema has not only the "capacity" of becoming developed, but also the power of actually effecting development; and the same energies must be attributed to the cytoblastema of the perfectlyformed animal. If this be granted, and it is a position which no philosophic anatomist would be inclined to doubt, it follows that, in the first class of epigeneses, or those in which, to borrow the author's words, "the epigenesis takes place in a manner perfectly analogous to that which occurs in healthy nutrition," so far from the influence of the cytoblastema *This is erroneous; a divided muscle is united by a cicatrix of dense areolar tissue. 1847.] Value of Schwann's Theory. 439 being, as asserted, at its minimum, it is in reality the efficient cause of the whole phenomena. As regards the second class, comprising scirrhus, encephaloid, tubercle, &c., so far, again, from there being any evidence that the surrounding tissues are the determining cause of the development of the cytoblastema, it is seen that the latter, when it has undergone its morbid metamorphosis, has, in the first place, no resemblance whatever to the tissue around which, in accordance with the theory, it ought to have; and in the second place, that whatever may be the tissue in which the deposit takes place, whether in the areolar tissue, in a gland, a muscle, or a bone, the new matter always presents the characters proper to its peculiar nature. Tubercle, for example, always offers the same aspect and microscopic appearances wherever it is examined, in the brain, in the lungs, or in the testis. Although, at the first blush, it may seem that the hypothesis which attributes the act of development to the surrounding parts, especially in the first class of epigenesis, where it is said, in obedience to what the author proposes to call "the law of analogous formation," that bone forms bone, and muscle produces muscle, is a probable explanation; yet, when closely scrutinized, it is beset with difficulties. If the blood-vessels are supposed to be the controlling agents, what notion can we form of their modus operandi? The actions of these organs have been very much curtailed by the exact anatomy of the present day: and under no reasonable supposition can they be admitted to act beyond their defined limits, in the manner in which they must operate, if they be the formative agents. Then, with respect to the nerves, it is positively known that their power is not essential to nutrition; a considerable part of the chick, for instance, is formed before the nervous system appears; and in plants there are epigeneses, but there are no nerves. If, in answer to the opinions we have advocated, it be said that it cannot be understood how it happens that from one of the same substance, fibrin, such a multitude of different products arise; a sufficient reply is furnished by the fact, that tissues as diverse from each other are in the chick, in obedience to the mysterious laws of organization, formed from and by that one material or cytoblastema lying beneath the area germinativa. It is, however, probable, as indeed Vogel himself surmises, that the cytoblastema is not always the same form of fibrin; and that in these modifications may be found one of the causes leading to so many heterogeneous productions. In considering individual new formations, the author premises some general remarks on the cell-theory of Schwann, in the truth of which, as applicable to morbid productions, he, on the whole, coincides; but, like other observers, he finds it necessary to restrict or to qualify the general position that all tissues spring from nucleated cells. Thus, in scrofulous and typhous exudations, and in a great part of the cases of tubercle, there is at first a finely granular or even an amorphous matter, which by degrees breaks up into a more or less fluid magma, with irregular molecules, but no true cells. As this subject has on several occasions been considered in this Review, it will suffice to extract the following paragraph, in which the general views of Dr. Vogel are stated:— "That this mode of development from cells occurs in pathological epigeneses may be readily shown in numerous cases. This process can be most obviously |