TISSUES, ORGANS, AND SYSTEMS. 97 



according to Schwann, also, at first, yields no gelatine, and therefore it 

 is no objection to the above view of the nature of Wharton's gelatinous 

 tissue, that it yields no gelatine on boiling, as Scherer has found. How 

 the collagenous matter is formed out of cells, whether the contents only, 

 or the membrane also, takes part therein, it is very difficult to say ; in 

 any case, from what we know of the contents of embryonic cells, it can 

 hardly be any but a protein substance which yields the gelatine, and, 

 from what takes place in the ossification of the cartilage cells, it seems 

 very probable that the cell-membranes and contents together become 

 metamorphosed into a collagenous substance. 



The morphological change which the formative cells of the connective 

 tissue undergo, in the course of their passage into bundles of fibrils, is 

 very probably this, that after their membranes and contents are fused 

 into a homogeneous semi-solid mass, they then secondarily break up into 

 fibrils ; the latter process taking place in the same manner as we see it 

 occur in the contents of the animal muscular fibres. Herewith, as a 

 rule, the nuclei of the cells eventually disappear, or if they remain, as 

 we see occasionally in connective tissue, still they never become changed 

 into the so-called nucleus fibres. 



Though in physiological connective tissue, development from cells 

 must be most decidedly affirmed, it does not therefore follow that a sub- 

 stance which chemically and morphologically closely resembles con- 

 nective tissue, may not arise in a different manner. We know, in fact, 

 that the collagenous basis of cartilage, when it breaks up into fibres, 

 becomes deceptively similar to connective tissue, and furthermore, that 

 fibrous exudations may become changed into a fibrous substance which 

 is scarcely, perhaps not at all, to be distinguished from genuine con- 

 nective tissue. There also exists, however, a pathological true connective 

 tissue in cicatrices of all kinds, and perhaps elsewhere, which is deve- 

 loped frojn cells; and for my own part, therefore, I am opposed to the 

 classing together of all connective tissues. We must in our classifica- 

 tions not only distinguish similarity or identity in structure and chemi- 

 cal composition, but embrace all the conditions, and especially the 

 genesis; and thence we must distinguish both the collagenous fibrous 

 cartilage and the collagenous organized fibrine, from true connective 

 tissue, just as we separate the true elastic fibre, from the chemically 

 and morphologically, very similar fibres of the reticulated cartilages and 

 from certain forms of metamorphosed fibrine. On the other hand, the 

 connective tissue which has not been developed from cells, may justly 

 and properly be arranged with cartilage.* 



* [The arguments brought forward by Professor Kolliker in support of his views with 

 regard to the nature and mode of development of connective tissue, appear to us not to 

 preponderate against those of Reichert, Virchow, and Remak, and to be opposed to 



7 



