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PRODUCTS, ADVENTITIOUS. 



exist between them. This substance may be 

 fluid or solid. Fluid intercell substance is 

 nothing more than non- solidified blastema; 

 the solid variety is amorphous, or composed of 

 fibrous pseudo-tissue. 



4. The PHYSIOLOGY of Growths com- 

 prises the phenomena of their origin, en- 

 largement, decay, elimination, cicatrization 

 and local reproduction, phenomena which, 

 it appears to us, can, only by misapprehension 

 of their true relations, be included under the 

 head of the Pathology of these Formations. 



All that is known actually, or surmised 

 upon fair grounds, concerning the origin of 

 Growths, has already been stated in our gene- 

 ral remarks on Blastemal Formations. 



The enlargement of Growths is effected by 

 the reception and evolution of nutritious 

 matter. Growths receive this matter from 

 vessels ; these vessels either permeate the 

 mass generally, supply portions only of its 

 substance, or merely reach a greater or less 

 extent of its surface. In the first case, the 

 growth is said to enlarge by intussusception ; 

 in the third, by pure imbibition ; in the second, 

 by both means. These distinctions are less 

 important than they on first view seem ; the 

 perfect nutrition of the extra- vascular natural 

 tissues proves, as a general fact, the vigour 

 and efficacy of the imbibition-process ; and in 

 truth imbibition is at play in all nutritions, 

 for the nutrient elements of vascular tissues 

 must be imbibed through the coats of their 

 vessels, and (it may be) in addition (as in the 

 instance of the endosteal lining of the canals of 

 Havers, and the subjacent osseous substance) 

 through a stratum of cells. Enlargement by 

 intussusception differs therefore from that by 

 imbibition, in degree rather than in kind. In 

 whichever way conveyed to the seat of Growth- 

 formation, the nutrient material, at first fluid, 

 is evolved and appropriated by continuous 

 cell-generation. Now this cell-generation 

 may be effected on an endogenous or an exo- 

 genous plan. When the plan is endogenous, 

 the germs of young cells are contained and 

 evolved within elder ones ; these secondary 

 cells are endowed with a similar procreative 

 faculty; the tertiary series are in like manner 

 fecund, and so on. Here a single cell may be 

 regarded as the potential embryo of an entire 

 growth. When, on the other hand, the plan 

 is exogenous, the germs of new cells are not 

 found within, but lie, and are evolved, outside 

 old ones. 



Where endogenous evolution prevails, and 

 a cell is, potentially considered, a tumour in 

 futuro, the perpetual production of similar 

 cells is easily intelligible; the offspring that 

 follows is as the parent that went before. 

 But in exogenous Growths the continuous 

 germination of infinite series of like cells is 

 not readily conceived. It may be surmised 

 (and the surmise amounts rather to a modified 

 expression of the fact than an explanation), 

 that when a series of cells has sprung into 

 being, this series acts on the evolution of 

 succeeding ones, as a natural vascularized 



surface is known to do on the generation of 

 epithelium cells ; the formed series so in- 

 fluences newly-exuded blastema (of which 

 it constantly excites the accession), that this 

 shall produce a new series of cells similar to 

 itself. But, however the perpetuation of 

 like cells be understood, be it remembered 

 that the thing itself has its limits ; for, as 

 we have just seen, deposits may appear in 

 Growths, pseudo-tissues are among their fre- 

 quent constituents, and a growth of one kind 

 may establish itself a nidus within the area of 

 another generically dissimilar. 



Elder cells thus seem (within certain 

 limits) to cause the increase, and regulate the 

 qualities, of younger ones. Younger cells are, 

 on the other hand, more or less active agents 

 in effecting the destruction of the elder ones : 

 less so in endogenous Growths, where the 

 elder may increase materially in size (as their 

 contained brood multiplies), and acquire 

 thickened walls; more so in exogenous 

 Growths, where such enlargement of cells is 

 not witnessed, and where the production of 

 young is coeval with the disintegration of 

 old ones. 



Such are the modes of production and in- 

 crease of cells, considered in their general 

 relations to themselves and to the mass they 

 form. We must now view cells as individual 

 existences, and inquire into the process by 

 which they are each developed ; and our 

 knowledge of this process is as yet limited 

 and unsettled. The spherical cell appears to 

 be produced on three distinct plans, (a.) Gra- 

 nular matter, precipitated from the fluid 

 blastema, accumulates sufficiently to form a 

 minute solid body (cytoblast or nucleus), 

 from and around which the cell-wall forms. 

 (6.) The cell is a molecular hollow body 

 from the first, and, as it grows, produces 

 within itself, or in its wall, a secondary body, 

 the nucleus, the cytoblast of a future cell, 

 (c.) The cell is, from the first moment of its 

 existence, complete in all its parts, consisting 

 of a cell-wall, a nucleus, and fluid contents ; 

 its development consists in the progressive 

 and justly-proportioned increase of all these 

 elements. The caudate cell is held to arise 

 (as already hinted) from the prolongation of 

 opposite points of the wall of a spherical cell ; 

 but there is no proof that cells may not exhibit 

 this shape from the first moment they are 

 possessed of form at all. Lastly, the ele- 

 mentary fibre is held to be formed in three 

 different modes, (a.) A spherical cell having 

 undergone elongation so as to become cau- 

 date, loses by still increased elongation and 

 flattening, the characters of a hollow cell 

 altogether ; a nucleated fibre is the result. 

 (b.) Elongation and linear juxtaposition of 

 nuclei effect the formation of fibre, (c.) Or, 

 it is held, fibres form as such from the 

 first moment shape is assumed ; no cell, or 

 nucleus-stage having pre-existed. All these 

 points are yet subjudice. 



The plan of enlargement and mode of 

 arrangement of the ultimate elements of 



