Oldalképek
PDF
ePub

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

traced in the formation of pus-corpuscles, when they are produced from a fluid blastema on a free surface, or in a cavity connected with the exterior of the body. In such a case, we first observe numerous isolated granules, which become surrounded by a very delicate transparent cell-membrane, which subsequently forms so thick and opaque a wall, that the nucleus can no longer be seen through it; on the addition of acetic acid, which dissolves the cell-wall, or at any rate renders it transparent, the nuclei again become visible. If it is impossible to trace the whole course of development in one and the same cell, we can yet make out the successive changes of the whole mass of cells with sufficient certainty. These and similar observations, such as for instance may be made on the formation of epithelium, confirm the opinion, that in all essential points Schwann's theory is applicable to morbid formations; but that, in individual cases, many facts may be observed which do not coincide with this theory, or at least render some modification imperative."P. 118.

The 5th Chapter treats of the special characters of pathological epigeneses, both fluid and solid, and, from the numerous subjects investigated, occupies the larger portion of the present volume. The section relating to purulent matter does not contain anything so novel or important as to require notice, nor indeed do several of those which succeed, concerning the epigenesis of areolar tissue, of blood-vessels, &c.

In speaking of melanotic productions, it is stated, that although the black matter is sometimes contained, as in the case of normal pigment, in true cells, usually however irregular in form, it frequently happens that these are wanting, the pigment molecules being deposited in the parenchyma of the affected organ. Although this description corresponds with what is seen in a microscopic inspection, yet it is questionable whether the pigment is ever deposited originally except in cells; at least the wellascertained phenomenon of secretion in other tissues is opposed to any other conclusion. The scattered molecules seen in their sections may be accounted for by the rupture and disintegration of pre-existing cells.

The former history of facial neuralgia, in which, after the operation of dividing the affected nerve, the pain often returned, sufficiently indicated that the nervous tissue was capable of reproduction; an inference since substantiated by the observations of Nasse and others, who have found that, after division, and indeed when small portions were excised, the fibres of nerves become re-formed in part, but they are somewhat smaller in size and fewer in number than in the normal state.

The attempts hitherto made to classify tumours have not been very successful; we do not, however, for that reason despair of an object so important to external pathology being accomplished. There is a very obvious cause of failure in the fact, that in order to determine the essential characters of tumours, microscopic observation is one of the principal means involved; and we need not remark that this mode of investigation is of very recent application, especially in this country. That it may often be used most advantageously in practice, we had recently a very conclusive proof, in a case of subcutaneous tumour removed in one of the metropolitan hospitals. The operator, from the suspicious appearances of a part of the diseased mass, and from its indurated character, was apprehensive that it was of a malignant nature, though another distinguished surgeon thought it was merely a modification of lipoma. To decide this somewhat doubtful point, a section of the above part was submitted to the

1847.]

Classification of Tumours.

441

microscope, when the whole was found to consist of two normal tissues, the adipose and the areola, and the fears of malignancy were satisfactorily removed. Another instance occurs to us of a supposed scirrhous disease of the testis, which was clearly proved, by minute examination, to be nothing more than a deposit of scrofulous matter. Now, as it is one of the highest privileges of our science to solace human suffering, an unerring test, and this in many instances microscopic inspection affords, which will enable the surgeon, not by a mere guess unsatisfactory to himself, but with an assured conviction of the truth of his diagnosis, to inform the patient and his friends that a previously doubtful tumor is not malignant, would be to a conscientious practitioner a thing of great price. For these reasons we do not concur with the opinion of the author, that "all attempts to arrange tumours (as we do animals and plants) into genera and species, must necessary fail." On the contrary, the very attempts made in the present and other works, and which, imperfect as they still are admitted to be, are of primary importance in practice, pre-suppose that there is a natural system, as in all branches of science.

The classification of Dr. Vogel has nothing of novelty in it, as our readers will gather from the subjoined extract.

[ocr errors]

"In a histological point of view, tumours may be arranged in two great divisions. To the first belong those whose elements may be considered histologically to agree with those of the normal body, and which further being once formed, discharge the duties of the normal constituents of the body, take a part in the general metamorphosis of tissue, and are nourished and increased like other parts. These are homologous, non-malignant tumours.

"In the second division, we must place those whose elements in a histological point of view differ more or less from those of the normal body, and which (as in the process of suppuration) from their nature give way, soften and destroy the organic parts which surround them or which they enclose-heterologous, malignant tumours."-P. 203.

In the account of the individual groups many interesting details are given, which we regret our limits prevent us noticing, excepting in a cursory manner, The great obscurity in which the tumours of bone are involved, renders all judicious attempts at simplification and distinctness acceptable. In this respect the several sections treating of fibrous, cartilaginous, and osseous tumours, may be studied with advantage. Those consisting of cartilage have been divided, since the excellent researches of Professor Müller, into two groups; the first consisting of true cartilaginous tumours, usually appear as hypertrophy and abnormal growth of bone (as callus, exostosis, &c.), and gradually pass into the osseous tissue; the second, distinguished by the term enchondromata, on the contrary, do not ossify, although they occasionally offer some ramifying corpuscles suggestive of the well-known osseous lacunæ or bone-cells. Enchondroma appears under three distinct forms; two of which occur in the bones, and a third, much more rarely, in soft parts, especially in glandular organs, as the parotid, testis and mamma.

"It forms a roundish, and generally smooth tumour of variable size, which on a section being made allows even the unaided eye to recognise two distinct constituents, one fibro-membranous, and the other gray, transparent, and soft, resembling firm jelly or softened cartilage. The latter element shows under the

« ElőzőTovább »