OF THE SIMPLE FIBROUS TISSUES. 229 



which the fibres of this tissue seem to be characterized ; and sometimes perhaps 

 undergoing a partial or complete development into cells ( 221). The rate at 

 which the production of fibrous tissue takes place in the manner now described, 

 is at first very rapid ; well-marked filaments being detectable in the blastema 

 within seven or eight days; and the tenacity of the bond thus formed between 

 the two ends of a divided tendon is such, that, in one^of Mr. Paget's experi- 

 ments, within ten days after the operation, the reunited tendo-Achillis of a 

 rabbit (the new tissue being a cord of not more than two lines in its chief dia- 

 meter) supported a weight of above fifty pounds. The subsequent changes take ' 

 place more slowly; but the repartition of divided tendons has been found to 

 be so complete within five months after the operation, that no trace of the sec- 

 tions could be discovered even by microscopic examination. It is important^ 

 observe that the blastema which undergoes this self-organization, is not an in- 

 flammatory exudation, but one which is much better adapted for the reparative 

 process. For, as Mr. Paget has observed, in experimenting upon the sub- 

 cutaneous division of tendons, the effusion which is first poured forth after the 

 shock of the injury contains exudation-cells, which begin to undergo the changes 

 described in the preceding paragraph, but are not developed beyond the state 

 in which they appear spindle-shaped. And it is not until about forty-eight 

 hours have elapsed (in the rabbit), that the true reparative material begins to 

 appear. This material must be looked upon as having undergone a much higher 

 elaboration than the inflammatory exudation has received ; since it can at once 

 pass on to that ultimate condition, which is only attained in the other case by 

 an intermediate process of cell-life. But we can scarcely fail to recognize, also, 

 the influence of the healthful condition of the surrounding tissues, in promoting 

 development by the vital force which they impart ( 27); the state of inflamma- 

 tion being essentially one of diminished vitality of the solid tissues, and its 

 existence therefore rendering them less liable to promote the organization of 

 the plastic material thrown out in their proximity. Accordingly we shall find 

 hereafter (CHAP. xi. SECT. 3), that in proportion to the degree of the inflam- 

 matory change in the solids, does it tend to depress the vitality of the effused 

 blastema, so as to retard or even to prevent its due development, and to occa- 

 sion the degradation of the whole or of the greater part of it to the condition of 

 pus. 



225. At what precise time, or by what means, the chemical change occurs, 

 by which the fibrinous constituents of the plastic exudation are converted into 

 the gelatinous basis of the white fibrous tissue, we have no certain knowledge ; 

 there are indications that the process is a gradual one, and involves the exist- 

 ence of various intermediate gradations ( 30) ; and a more attentive chemical 

 examination of fibrous tissues in progress of formation, would probably throw 

 considerable light upon the nature of the transition. All that is known of this 

 subject, however, indicates that the production of the gelatigenous tissues takes 

 place solely at the expense of the fibrinous component of the blood ; and that 

 gelatin employed as food cannot become converted into fibrous tissue, except 

 by passing through this intermediate condition, into which it is next to certain 

 that it can never be transmuted. For although there is ample evidence of the 

 conversion of the albuminous compounds into the gelatinous, in the living body, 

 yet the reconversion of the gelatinous into the albuminous appears to be a com- 

 plete impossibility. (See CHAP, vii.) 



2. Of the Fibro- Cellular Membranes, and their Appendages. 



226. The body of Man, in common with that of all the higher animals, con- 

 tains numerous and extensive membranous expansions, which form its external 

 investment and line its internal cavities, and which are consequently free or 



