Tue Microscopr. 185 
in this manner is the ferment. Osler has examined the rela- 
tion of the blood-plaque to coagulation experimentally, and his 
results are very interesting. If an ordinary ligature, partly: 
teased out, be passed through the femoral vein of a dog and al- 
lowed to remain for five or six minutes, or less, the threads be- 
come coated with the plaques; and the same coating of plaques 
may be obtained by whipping freshly drawn blood with a bunch 
of threads, as in Bizzozero’s experiment. The threads are then 
carefully washed in a saline solution, by which the red corpus- 
cles are removed. If the threads be then dipped into a coagul- 
able solution clotting occurs. But Rauschenbach criticizes this 
experiment by saying that the threads may have absorbed fer- 
ment which was not washed away; and that the coagulable fluid 
used by Bizzozero is only a test for free ferment. Kemp thinks: 
that the first objection is valid, but Osler replies to it by saying 
that the chief elements in the clot are plaques; and the greater 
the number of the plaques the denser the coagulum. To the 
second Kemp replies that by granting it we exclude the leu. 
cocytes adhering to the threads from a share in the formation of 
the ferment, if any isformed by what does adhere to the threads. 
It then remains to explain why the time of coagulation should 
depend upon the number of plaques, and the experiment re- 
mains of value as offering strong support to the theory that the 
ferment may be derived from the plaques. 
But there is further and more conclusive evidence of the 
participation of the plaques in the process of coagulation, as 
afforded by the experimental production of thrombi. So far as 
completed Kemp’s work in this direction tends to confirm the 
results of Osler, Bizzozero, Hayem, Ferraro and Lubnitzky, 
who find that the white thrombus is not composed of leucocytes 
but of plaques; that is due to an agglomeration of plaques 
around a lesion in the vascular wall, or a foreign body intro- 
duced into the vessel. The plaques are the elements which 
first settle on the edge of the wounded vessel, and form the 
basis of the clot, as shown by Eberth, though he still holds to 
the idea that the leucocytes play an important part in the for- 
mation of white thrombi. Osler contends that they are com- 
posed chiefly of plaques, and that their further development 
results from the disintegration of the plaques; that a granular 
