r 407 ] 
■dilpofition ; but the patient got well without re- 
peating the evacuation. 
It may be mentioned here, that I have once or 
twice ieen blood, which, when it firft began to 
coagulate, had on its furface a red pellicle, and under- 
neath a tranfparent fluid, which afterwards formed 
a cruft. In thefe cafes, if the red pellicle had not 
been removed before the reft of the blood had 
congealed, we might have concluded that no part 
of the blood had this difpofition to form a white 
cruft. This appearance, I fhould imagine, was owing 
to the blood, where in contact with the air, having 
coagulated very early, and therefore before the red 
particles had time to fublide, from that part of the 
lymph which had its difpofition to coagulation leflened. 
The learned profefl'or de Haen has taken notice of 
a curious appearance of the blood, which he could 
not account for ; but which, I presume, may be 
explained from fome of the above experiments. His 
obfervaiion is, “ That, having bled a perfon in a fever, 
“ the b'ood was covered with an inflammatory cruft, 
* c and upon examining the cr ajjamentum in one of 
“ the cups, it formed a fort of fack containing a 
“ clear fluid : this fluid being let out, and the whole 
“ covered and fet by, on examining it next morning, 
“ a very firm cruft covered the whole again, and 
<c extended to the bottom of the cup*.” I once 
met with a cafe fimiiar to this ; for, having bled a 
perfon into four cups at ten o’clock in the morning, 
on looking at the blood afterwards, at five in the 
afternoon, I found the jerum had not feparated 
from the cr ajjamentum in the firft cup j but the 
* Vide Rat. Medendi, cap. vi. 
