182 Sir Everard Home on the changes the blood 
thus let loose, pervaded the surrounding fluid into which it 
is,- propelled , in any particular manner. With a view to 
determine this point, I wounded the skin of my arm 
with the point of a lancet, so as to draw a drop of blood, 
which was received into a watch glass in a fluid state, and 
placed in the field of the microscope. The eye was then kept 
constantly fixed upon it, to watch the changes that might 
take place. The first thing that happened, was the formation 
of a film upon the surface, that part beginning to coagulate 
sooner than the rest. In about five minutes, something was seen 
to be di sengaged in different parts of the coagulum, beginning 
to show itself where the greatest number of globules were 
collected ; and from thence passing in every direction with 
considerable rapidity through the serum, but not at all 
interfering with the globules themselves, which had all dis- 
charged their colouring matter; wherever this extricated 
matter was carried, a net- work immediately formed, anasto- 
mosing with itself on every side, through every part of the 
coagulum. When the parts became dry, the appearance of 
a net-work remained unaltered. In some instances, bubbles 
were seen to burst through the upper surface of the coagu- 
lum : this, however, did not prevent the ramifications that 
have been described from taking place. The annexed Plates 
give the exact representation of the appearance the blood 
taken from my arm put on , when it coagulated and became 
dry, as shown in the field of the microscope. [PI. ix,x.[| 
If the blood is cold when it is exposed in the microscope, 
and there is a larger quantity of serum upon the glass, the net- 
work is only formed in those parts where clusters of globules 
are collected; and when the serum dries, it cracks, and spoils 
