168 LECTURE VII. 



variations exhibited by these fibres when forming out of 

 the blood have reference to their size and breadth ; 



these are peculiarities con- 



Fio. 50. . , . , . , 



cernmg which it has not 

 hitherto been possible to form 

 any certain judgment. I meet 

 with these variations pretty 

 frequently, but without being 



in a position to assign the causes which determine them. 

 The extremely fine and delicate fibres are those usually 

 met with ; but sometimes we find far broader, and 

 almost ribbon-like fibres, which are much smoother, but 

 in other respects, cross and interlace in pretty nearly 

 the same manner. Essentially, therefore, there is always 

 present in a clot a network composed of fibres, in the 

 meshes of which the blood-corpuscles are enclosed. If 

 a drop of blood be allowed to coagulate, fine filaments 

 of fibrine can be seen everywhere shooting up between 

 the blood-corpuscles. 



With regard to the nature of these fibres, we may 

 observe that there are only two other kinds which, his- 

 tologically speaking, bear at all a near resemblance to 

 them. The one kind occurs in a substance which, 

 singularly enough, effects an approximation between the 

 most ancient, perfectly antique, craseological ideas and 

 the modern ones, namely in mucus. In the old Hippo- 

 cratical system of medicine the whole mass of fibrine is, 

 as is well known, included under the terms phlegma, 

 mucus, and when we compare mucus with fibrine, we 

 are obliged to confess that there does indeed exist a 

 great similarity between them in the form they assume 

 upon coagulation. In a similar manner to fibrine, 



Fig. 50. Coagulated fibrine from human blood, a, Fine, 6, coarser and broader 

 fibrils, c, Red and colourless blood-corpuscles enclosed in the coagulum. 280 

 diameters. 



