Tue Microscope. 181 
SELECTIONS. 
THE BLOOD-PLAQUES AND COAGULATIGN. 
In the last number of Zhe /ournal, (see this journal for 
July,) we attempted to give some idea of the blood-plaque, and 
showed that while there is very strong evidence that it is an in- 
dependent element of the blood, there are also strong reasons 
for believing that it is what Hayem terms an hzmotoblast, or 
yonng red corpuscle. But which of the theories be held mat- 
ters but little in considering the relation of the plaque to the 
process of coagulation. This, however, is best prefaced by 
some account of the histology of the formation of fibrin, and 
its relation to the histological elements of the blood, including 
the blood-plaques. 
Inthe study of the formation of fibrin under the micro- 
scope it has long been noticed that the fibrin filaments spread 
out as rather distinct rays from the minute aggregations known 
as Schultze’s granular masses. This was noticed by Schultze, 
and by Ranvier in 1873, who regarded them as centres of coag- 
ulation; and also by Riess, Hayem, Leube, Bizzozero and oth- 
ers. Ranvier, Davidson, Bizzozero and Halla think that there 
is a distinct and direct connection between the fibrin-threads 
and the granular masses, but Schultze thinks that the threads 
do not proceed from the masses, but pass over or through them. 
Heyl, having observed that in Bizzozero’s fluid the number of 
granular masses increases as the leucocytes decrease, and that 
both the granular masses and leucocytes stain with methyl 
violet, has drawn the new unwarranted conclusion that on the 
assumption that the leucocytes break down during coagulation, 
the granular masses are derived from the leucocytes. This 
view has received the support of Hlava and Riess, but is denied 
emphatically by Osler and Laker; and Léwit, after a careful 
study of the coagulation of lymph under the microscope, has 
found nothing that can be regarded as leucocyte detritus. The 
generally accepted view as to the gaanular masses, then, is that 
they are formed by the plaques. 
In the very careful study made by Kemp he found that the 
formation of the granular masses by the plaques may be seen 
2 
