224 MORBID STATES OF THE BLOOD, ETC. 



corpuscles joined in pairs ; and it is only on account of the 

 rapidity with which the hlood is forced through the arteries, and 

 repeatedly transmitted through a system of innumerable canals 

 of very narrow calibre, that no permanent union between these 

 elements normally occurs. 



Assumino- tliat a clot has reached a certain size, and that a 

 fresh layer of coagulated blood has just been deposited upon its 

 surface, it is clear that of all the blood-corpuscles which are 

 carried past it, the colourless ones, owing to their glutinous 

 properties, will be the first to adhere to it, and to become station- 

 ary in its outer parts ; just as in RecJdlnghausen s experiments 

 on suppurative inflammation, excited by the introduction of a 

 finely-porous body into the subcutaneous tissue, the pus-cor- 

 puscles penetrate into the pores, and thickly infiltrate the margins 

 of the foreign hodj. Well, a layer of leucocytes is deposited 

 which clothes the thrombus for a time, until a fresh deposit of 

 red coagulum takes place. In other words, the blood coagulates 

 by fits and starts, and between each recurrence, a large number 

 olF leucocytes have time to attach themselves firmly to the surface 

 of the clot. 



On making a transverse section through a clot of this kind 

 we see at once that it i.-^ permeated in every direction by a system 

 of transparent lines whi.-li exhi])it a more or less distinctly con- 

 centric arrangement. These Hues correspond to the cross section 

 of the layers of leucocytes which alternate with broader la}'ers 

 of ordinary red blood. We must accordingly distinguish between 

 two kinds of thrombi, basing our division on the differences in 

 their primary structure : 



1. Xon-laminated thrombi, originating in the sudden coagu- 

 lation of an isolated quantum of blood. 



2. Laminated thrombi formed by an intermittent, gradual, 

 and long-continued coagulation. 



§ 190. A clot is susceptible of further metamorphosis in two 

 different directions, that of organisation and that of softening. 

 Organisation, or transformation into connective tissue, has hitherto 

 been chiefly studied in the non-laminated thrombi of the larger 

 vessels. The following account must therefore be understood to 

 apply to these only, and must not be supposed to include the 

 oro-anisation of laminated clots, concerning which we are at 

 present entirely ignorant. The thrombus attains its maximum size 



