PRODUCTS, ADVENTITIOUS. 



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PRODUCTS, ADVENTITIOUS. The 



difficulty of defining the term Adventitious 

 Product with precision has so frequently been 

 acknowledged, that we feel extremely diffident 

 in offering a new attempt to the consideration 

 of morbid anatomists ; the more so as the re- 

 cent disclosures of the microscope would pro- 

 bably strike the generality of persons as 

 having, almost of necessity, simplified the 

 task, while they have in reality rather in- 

 creased its perplexity. Fully conscious, then, 

 of the debatableness of the ground we tread 

 on, we would apply the term Adventitious 

 Product to any substance ivhich, either pro- 

 duced by or developed in connection with the 

 animal frame, neither forms a natural consti- 

 tuent element, nor a natural secretive product, 

 of the structures amid which it is evolved. The 

 qualification, " either produced by or deve- 

 loped in connection with the animal frame " is 

 required to ensure the exclusion of Foreign 

 Bodies ; and the latter member of that quali- 

 fication, " developed in connection with the 

 animal frame," as plainly necessary to ensure 

 the inclusion of Parasites, which (whether 

 they be the proceeds of equivocal generation 

 or evolved from germs introduced from with- 

 out) are certainly not produced by the textures 

 containing them. 



Understood thus, (and the signification 

 seems the widest that can, in a practical point 

 of view, be given to the term,) the character 

 of adventitiousness is conceived to arise in 

 three different ways: a substance may, in 

 truth, be adventitious, because its nature is 

 different from that of any of the natural tex- 

 tures and secreted materials ; or because the 

 form it has assumed differs from that under 

 which it naturally occurs ; or because the situa- 

 tion it occupies is one to which such substance 

 is in the natural order of things wholly foreign. 

 Thus tuberculous matter is adventitious, be- 

 cause it differs in nature from all the elementary 

 structures and secretions j a calculus com- 

 posed of lithate of ammonia is adventitious, 

 because the form, assumed by the salt compos- 

 ing it, differs from that it wears as a constituent 

 of healthy urine ; and an ossification of the 

 pleura is adventitious, because the ossiform 

 structure forming it occupies a locality in 

 which, in the healthy state, bone is unknown. 



The amount of adventitious quality in pro- 

 ducts of these three kinds differs : it is greatest 

 and most clearly defined, where dependent on 

 the nature of the constituent material. Thus, 

 in the first place, concerning the adventitious- 

 ness of cancer or pus, no doubt can ever arise ; 

 their physical and chemical characters and their 

 essential nature are decisive of the point. In 

 the second place, when a product becomes ad- 

 ventitious simply from the peculiarity of its 

 localization, the question is often less clear ; 

 nor indeed can it in the existing state of know- 

 ledge be invariably settled. Muscular fibres 

 have, for instance, been met with in the walls 

 of the ureter ; albumen is excreted in great 

 quantity with the urine in certain states of dis- 

 ease : but whether such muscular fibres are to 

 be considered evidences of hypertrophy or ac- 



tual new products, and whether such albumen 

 must be viewed as a totally new material of 

 renal secretion, or as a natural element of urine 

 in excess, depends upon the mode of decision 

 of the preliminary questions, whether rudimen- 

 tary muscular fibres do or do not naturally exist 

 in the situation referred to, and whether albu- 

 men do or do not, in excessively small propor- 

 tion, form a natural constituent of human urine. 

 And this is not the only aspect under which it 

 becomes practically difficult to distinguish hy- 

 pertrophous from adventitious products. The 

 two states are in some conditions of disease 

 distinctly and intimately associated. Thus, in 

 eburnation of the heads of bones, the proper 

 osseous tissue undergoes hypertrophy only, 

 while the adjacent articular cartilage becomes 

 infiltrated with adventitious bone. Again, the 

 fat, which forms in abundance in the liver in the 

 so-called " fatty degeneration " of that organ, 

 is at first merely an excess of that naturally 

 existing in the hepatic cells, and can there- 

 fore only be regarded as a product of unhealthy 

 supersecretion : but with the advance of the 

 morbid change, the inter-cell texture of the 

 organ becomes infiltrated with fat j and this fat 

 is an adventitious product by reason of the lo- 

 cality it occupies. Nature here, as elsewheue, 

 transgresses the artificial limits established for 

 the facilities of study. In the third place, it is 

 clear that newness of/orw implies the quality 

 of adventitiousness in an inferior degree only 

 that a material naturally existing dissolved 

 in a secreted fluid, for example, does not, when 

 from physical or chemical causes it accumulates 

 in solid masses, possess the quality in question 

 to the same amount as another which is never, 

 under any shape nor even in the minutest pro- 

 portion, a natural existence. 



The great number and variety of the objects 

 to which the term Adventitious Product, de- 

 fined in the manner we have just proposed, 

 win apply (from a microscopical crystal, for 

 instance, to the highest species of intrinsically 

 vegetative Growths) render it necessary, in 

 limine, to introduce some order into the sub- 

 ject. We shall consequently set out by tracing 

 those lines of distinction which separate from 

 each other the various objects united together 

 by the common property of Adventitiousness. 



It would, no doubt, be desirable and most 

 strictly logical to employ some one uniform 

 principle in establishing the various divisions 

 and subdivisions of this, as of all other groups 

 of natural objects, which require classification. 

 But in the present state of knowledge, at least, 

 systematic accuracy of this kind is unattainable. 

 Neither the anatomy of texture or of form, the 

 physical or chemical nature or properties of 

 ultimate elements, the mode of formation, the 

 physiological properties, nor the pathological 

 influences of morbid products, will, taken 

 singly, supply a feasible instrument of classifica- 

 tion. All must by turns be made to contribute 

 their share in the work. And as all previous 

 modes of arrangement have been found to 

 bear the impress of contemporary physiolo- 

 gical doctrines, so will the existing impulse 

 towards micrological study be traced in ours. 



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