FIBRINE, MUCUS AND CONNECTIVE TISSUE. 



mucus also forms into fibres, which frequently become 

 isolated and then coalesce, so as to give rise to certain 

 figures. The other substance which belongs here is the 

 intercellular, or, if you will, the gelatine-yielding sub- 

 stance of connective tissue, the collagen (gluten- of earlier 

 writers). The fibrils of connective tissue only differ in 

 that they are not usually reticulated, but run a parallel 

 course, whilst in other respects they resemble those of 

 fibrine in a high degree. The intercellular substance of 

 connective tissue presents another point of resemblance 

 with fibrine in the great analogy of its behaviour with 

 reagents. When we expose it to the action of diluted 

 acids, especially the ordinary vegetable acids, or also 

 weak mineral acids, the fibres swell up and disappear 

 before our eyes, so that we are no longer able to say 

 where they are. The mass swells up, every interspace 

 disappears, and it looks as if the whole were composed 

 of a perfectly homogeneous substance. If we slowly 

 wash it and again remove the acid, a fibrous tissue may, 

 if the action have not been too violent, once more be 

 obtained, after which the previous condition can be pro- 

 duced afresh, and changed again at pleasure. This 

 behaviour has hitherto remained unexplained, and for 

 this very reason Reichert's view, which I have already 

 mentioned, that the substance of connective tissue, is 

 really homogeneous and the fibres are only an artificial 

 product, or an optical delusion, has something alluring 

 in it. In fibrine, however, the individual fibres can, 

 much more distinctly than is the case with connective 

 tissue, be so completely isolated, that I cannot help 

 saying that I regard the separation into single fibres as 

 really taking place, and not merely as an artificial one, 

 or as a delusion on the part of the observer. 



But it is very interesting to observe that this fibrillar 

 stage of fibrine is invariably preceded by a homogeneous 



