184 Tue Microscope. 
compares the formation of fibrin to a sort of crystallization 
starting from small crystals already formed. Kemp says: The 
definite form which the fibrin-threads take, especially the typi- 
cal needle-shaped form of the threads when deposited isolated 
in scanty clot, speaks strongly in favor of a crystallization; 
while the subsequent toughening and contraction of the threads 
show a clear resemblance to the coagulation of certain proteids, 
notably myosin. In fact, it appears that we have in blood an 
interesting process which may be regarded as intermediate, 
in a certain sense, between a true crystallization on the one 
hand, and the coagulation of certain proteids, as myosin, 
etc., on the other. Hence Kemp thinks it evident that there is 
no histological connection between the plaques and fibrin, so 
that if the former are involved at all in coagulation the connec- 
tion must be a chemical one; in other words, the plaques must 
give up something to the plasma at the same time that they 
break down. But the strongest evidence of a connection be- 
tween the plaques and coagulation is derived from facts pointed 
out Hayem, Bizzozero, Lavdovsky, Halla, and Ferraro: that 
fibrin is formed part passu with the breaking down of the 
plaques; and that reagents or conditions which retard the 
breaking down of the plaques, retard to precisely the same ea- 
tent the formation of fibrin; and reagents which preserve the 
plaques prevent the formation of fibrin altogether. Kemp’s ob- 
servations, so far as completed, confirm these facts in every 
respect. 
The question now arises, what part do the plaques play in 
the process of coagulation? Hayem and Bizzozero think that 
their part is to furnish something essential to coagulation, and 
they agree that ferment is in all probability the agent in ques- 
tion. Now, in some experiments Kemp noticed that blood flow- 
ing through a dirty tube coagulated more quickly than in flow- 
ing through a clean glass tube; and he thinks that this would 
seem to show that in passing through the dirty tube the blood 
took up something which brought about coagulation before the 
plaques broke down, but which is also formed later by the 
plaques when they break down. And from what we know of 
coagulation at the present time, he says, it seems probable that 
the agent in fibrin-formation that would be more likely to act 
