98 GENERAL ANATOMY OF THE TISSUES. 



Literature. — C. B. Reichert, " Vergleichende Beobachtungen iiber 

 das Bindegewebe und die verwandten Gebilde," Dorpat, 1845; Luschka, 



our own observations, whicli agree in all essential points with those of the last-named 

 authors. 



There are two questions in dispute. The first, the structure of the connective tissue; the 

 second, the homology of its various constituents with those of other tissues, and of cells in 

 general. 



With respect to the first question, it is admitted on all hands that ordinary connective 

 tissue (e. g. of the tendons) is composed of two elements : a, a network of elastic tissue, 

 which is not acted upon by cold acetic acid ; b, a substance which is swollen up by acetic 

 acid, and has a more or less fibrillated appearance, contained in the meshes of the elastic 

 tissue. Now it has been demonstrated by Virchow, and the fact is admitted by both Kol- 

 liker (supra) and Reichert (Zur Streitfrage iiber die Gebilde der Binde-substanz, tiber die 

 Spiralfaser, &c., Mtiller's " Archiv," 1852), that the elastic fibres are originally cells, and 

 therefore that they are homologous with the cartilage-cell, i. e. the cartilage-cavity with its 

 \va]l plus the cartilage-corpuscle or nucleus. That this is the case is very evident upon ex- 

 amining in a yoimg animal (e. g. kitten) the insertion of the tendo-Achillis into the cartila- 

 ginous extremity of the os raids. It is here easy enough to see that the oval or rounded cells 

 of the true cartilage pass in the most gradual manner into the elongated elastic fibres of the 

 true tendon. The cells retain their cavities for a considerable time, but eventually the nuclei 

 and the thin layer of substance which immediately forms the wall of the cavity, become 

 fused into one mass, and altered in chemical composition. A like alteration afiects the 

 matrix in various irregular directions, so that the delicate elastic connecting fibres are formed, 

 and constitute a network through the whole tendon. These connecting fibres are often 

 branched, and even appear fibrillated at the ends, especially if torn out from their connection 

 vi^ith one another, and in this condition they exactly resemble the bodies figured by Professor 

 Kolliker as the " fusiform formative cells"' (Fig. 29.) That they have nothing to do with the 

 development of the "fibrillated" collagenous substance is, however, obvious, from this very 

 simple circumstance, — that the latter lies between them, and in jmrt replaces the rest of the 

 matrix of the cartilage, into which it can be directly traced. It will not be said in this case, 

 that the "fibrillated" tissue of the tendo-Achillis is only "deceptively similar" to true con- 

 nective tissue — and yet the transition of true cartilage into true connective tissue, is not less 

 certainly demonstrable in the intervertebral cartilages, &c. 



As Reichert, then, long since indicated, in illustrating his " law of continuity" (a law whose 

 full importance, it may be observed, has yet to be developed), and as he and Virchow have 

 since demonstrated, the elastic element of fully-formed connective tissue represents the car- 

 tilage-cells, while the collagenous element represents the matrix of the cartilage, and is not 

 developed from distinct cells. 



With regard to the structure of the latter element, Reichert, in his last communication, 

 after considering Koiliker"s arguments, denies the truth of his statement, that the ends of the 

 fibrils may be seen in transverse sections of the tendons (§ Tendon, infra,) and retains his 

 opinion that it is not truly fibrillated in the uninjured state, but that it is simply plaited. 

 Some remarkable observations upon the behavior of the "connective fibril bundles" with 

 acids and alkalies, to which Reichert first drew attention in 1S4G, and which have been 

 since extended by Dr. Paulsen (Bericht., Miiller's " Archiv," 1849), are, as the former points 

 out, of the greatest importance in determining the nature of this tissue, and remind one 

 somewhat of the equally puzzling structure of the starch-corpuscle. Dr. Paulsen states, that 

 if a piece of tendon be kept for twenty-four hours in a solution of caustic potash often per 

 cent, strength, it changes into a viscid hyaline mass, so transparent that it can hardly be dis- 

 tinguished from the surrounding fluid. This substance can be torn with equal ease in any 

 direction, and no fibrous structure can in any way be detected in it. Under the microscope 

 the mass is quite transparent, and shows no trace of the well-known striation. However, 

 the connective tissue is at this time by no means dissolved, nor is its texture destroyed. If 

 the potass be removed by acetic acid, and this, if it be in excess, by washing, the original 



