ON THE STRUCTURE OF TENDON. 137 



transverse section of a bundle is surrounded is composed of 

 parts of all cross sections of half-cell-cylinders of the con- 

 tiguous bundles. Now, should we conclude from the appear- 

 ances on cross sections that there is a sheath round the 

 bundle, then the meshes of the network ought to be of nearly 

 equal size, because the bundles of a tendon are all of nearly 

 equal thickness. But it is by no means a fact that the 

 meshes of the network seen on cross section are of nearly 

 equal size. On the contrary, on a very successful cross 

 section made from a very successful preparation, they are 

 found to differ mutually in a manner perfectly incompatible 

 with the constant thickness of the bundles. The appearance 

 is, however, readily explained by the fact that many of the 

 bundles touch on the surfaces that are free from cells ; to such 

 a group of cross-cut bundles the large meshes accordingly 

 correspond, while the small meshes are caused by the con- 

 tiguous bundles coming in contact with each other by sur- 

 faces all completely covered by the cell-mantle. On silver 

 specimens which have been brushed in serum one may occa- 

 sionally find the surface of the bundles at various depths, 

 which are not covered by rows of cells, exhibiting a finely 

 granular aspect, so that it is not very improbable that there 

 exists between the bundles an albuminous substance in which 

 these precipitations of silver occur. 



It has been pointed out by many observers^ that there exists 

 in the tendo Achillis of the frog, of some mammals, and also 

 in other tendons of the extremities — cartilage — and that 

 either real hyaline cartilage or only cartilage-cells. In 

 respect of the tendo Achillis, Boll distinctly denies the truth 

 of this ; for other connective-tissue substances where carti- 

 lage has been described among the connective-tissxxe, he 

 denies it also with more or less distinctness. Quite recently, 

 however, as regards the tendo Achillis of the frog. Boll has 

 been contradicted by Torok. And as far as the question 

 concerns the intervertebral discs I must distinctly deny Boll's 

 assertion that the cells in " so-called cartilage" are elastic 

 hyaline cell-plates, exactly as in tendon ;. and I cannot in 

 any way understand how this observer, who asserts that 

 he has investigated the structure of the tails of rats and 

 rabbits in transverse sections, could have overlooked the 

 cartilage of the intervertebral substance. On a longitudinal 

 section of the tails of these animals we find that the matrix 

 of the intervertebral substance consists of fibrillar bundles, 

 crossing each other at more or less acute angles. The 

 cells upon these bundles as well as between them have 

 ^ Lehman, Hoyer, Gegenbauer, and Giiterbock. 



