INFLAMMATION. 
2I 5 
The so-called invisible corpuscle of Norris is not to be seen 
in the intact blood as it is of exactly the same color and retrac¬ 
tile index as the liquor sanguinis, but can be readily perceived 
by draw ing off that fluid by any one of several ingenious 
methods. They are of exactly the same size and shape as that 
of a red blood corpuscle, i. e ., like a biconcave disc. 
The phenomena of motion and mode of circulation of the 
corpuscles, as observed by microscopic examinations, are wholly 
due to the laws which govern solid bodies of the same shape 
and specific gravity passing through small tubes in a similar 
liquid and are totally r independent of the heart, endothelium of 
the blood-vessels and vaso-motor nerves. The present century 
has removed this, as also many other facts, from the realm of 
the mysterious to that of the purely physical. 
In the normal state the haemocytes circulate with a gliding 
motion, having their diameters transverse to the long axis of 
the blood-vessel, if it is so small that one of them nearly or 
quite fills up its lumen; while the leucocytes roll along against 
its superior wall. Hayem’s' hsematoblasts, very minute, are in¬ 
terspersed among the red blood corpuscles in the axial portion 
of the vital current. 
Leucocytes more principally in the slow-flowing peripheral 
part of the stream, and being viscid, have a tendency to stag- 
nate and pass by migration through the walls when traversing 
the capillaries. I have searched in vain for facts as to the mode 
of circulating, followed by the invisible corpuscle of Norris. 
Such is the normal, physiological condition of the circula¬ 
tion in an organ. However upon application of any of the 
causes mentioned above, which produce inflammation, there re¬ 
sults, first of all, an irritation and congestion during the early 
stages of which the blood moves much more rapidly than usual 
and the corpuscles may be seen to dart through the capillaries 
with unwonted speed. This acceleration usually lasts for six 
or eight hours. Soon, however, owing to the increased blood 
pressure, much plasma is exuded into the surrounding tissue, 
leaving the corpuscles too dry to circulate rapidly. They be- 
