60 Dr. BealEj on the Germinal Matter of the Blood. 
The formation of a thread of fibrin. 
I have seen a thread of fibrin in process of formation. 
Sometimes when a drop of blood is placed upon a glass slide 
and covered with thin glass, it will happen that in consequence 
of the unequal pressure of the glass, rapid currents will occur 
in different parts of the thin layer. Red corpuscles will be 
seen rushing along in streams with great velocity, and here 
and there diverging in consequence of some impediment ; 
oftentimes a stream is split into two in consequence of being 
urged against a small body which adheres most forcibly to the 
glass. Now, the bodies which thus adhere to the glass 
are white blood-corpuscles. The red corpuscles are still 
carried along in the stream of fluid. A white blood- corpuscle 
thus adherent is often in part forced onwards, and thus a thin 
thread is formed, as shown in fig. 11. This thin thread I 
believe to be fibrin. When blood is poured into a glass or 
other vessel, the corpuscles which adhere to the sides, and 
which take active part in the formation of the coagulum, are 
the white co^yuscles. The red are entangled in the coagulum 
formed by the white corpuscles, but they are passive, and 
such a clot or coagulum may, as is well known, be formed 
altogether ivithout the red corpuscles. 
In an inflamed vessel " the bodies]which cleave to the sides 
are the white corpuscles j and it is easy to conceive how in 
this process a considerable mass of fibrinous matter might 
be formed, as upon the surface of a valve of the heart in 
cases where there was any little roughening, or where other 
changes had ensued in the membrane so as to favour the 
adhesion of white blood-corpuscles. In all these deposits 
occurring in the interior of the vascular system the white 
corpuscles are the agents most directly concerned. It is 
probable that upon the outer part of each white corpuscle is a 
thin layer of adhesive viscid matter, which may be con- 
sidered imperfectly formed fibrin. This adheres to any in- 
equalities of surface with which the corpuscle comes into 
contact. Being stationary, it contracts and gradually be- 
comes firmer and more condensed and at last assumes the 
characters of ordinary fibrin. The same changes continue 
to go on upon the surface of the corpuscle, and thus the 
fibrin accumulates. More corpuscles become entangled, until 
a mass of fibrin results, in the substance of which masses of 
