EXPERIMENTAL PATHOLOGY. 
233 
wo propose now to study. Indeed, during the hemorrhages the 
blood which passes between the edges of the vascular wound is 
always new; if this blood is collected in a basin it will not be¬ 
come a gelatinous mass for several minutes. Why, then, does a 
solid clot form itself between the edges of the open wound strong 
enough to resist the isssue of any more blood ? 
Let us see. After laying open the jugular vein of a dog we 
wait until the hemorrhage has ceased, and immediately place a 
ligature upon the peripheric end of the vessel, when we may 
easily extract from the wound a nail-shaped clot whose point 
penetrates the vascular cavity while its head is spread upon the 
external wall of the vein. If we immediately dip this clot in a 
liquid which fixes the elements of the blood, its microscopic ex¬ 
amination can be readily made, and the point and central portion 
are greyish, viscous and composed partly of granular and amor¬ 
phous matter. The granulations consist of enormous masses of 
hematoblasts, already altered, but still quite distinct from each 
other, the amorphous matter being the product of the union 
in mass, and solid, of the hematoblasts most altered. The head 
of the nail, which is red externally, has in its center a prolonga¬ 
tion of the liematoblastie viscous matter, and at its periphery 
fibrillre, containing a large quantity of red globules, while in 
the whole central portion, properly speaking, the closing part, 
very few white globules are seen. It is evident, then, that the 
fibrin has been added to the condensed cork, formed almost 
entirely of hematoblasts. 
The formation of the cork may be easily followed under the 
microscope in the mesentery of the frog. 
After exposing a middle-sized vein under the microscope, and 
making an incomplete section upon it, an abundant hemorrhage 
takes place at once, and for a few seconds nothing but a red mass 
can be seen around the wound. The flow of blood soon dimin¬ 
ishes audit runs more slowly until it is surrounded by a ring of 
elements firmly resting against each other, and adherent to the 
opening of the vessel. Some moments later the orifice of the 
wound becomes seared by a kind of whitish mass, through the 
elements of which the red globules enter with difficulty. Far 
