ON THE EARLY STAGES OF INFLAMMATION 225 
The dilatation differed in different instances, being generally more decided and 
more permanent when the water was hotter and longer applied.t_ In one case, 
water at 100° thrown upon the web for a brief period caused constriction for 
a few seconds in the artery under observation, followed by dilatation. While the 
vessels were still above their usual calibre, more water of the same temperature 
was applied as before, and again induced contraction followed by abnormal 
dilatation, which was again made to give place toconstriction by a third similar 
application : the experiments were repeated within a few seconds of each other. 
When water not higher in temperature than from 110° to 140° was thrown 
for not longer than a second or two upon a perfectly healthy web, the changes 
above described in the diameter of the arteries produced effects upon the flow 
of blood through the capillaries, precisely similar to those mentioned at the 
conclusion of the last section. Thus in one such case the constriction of an 
artery lasted for several seconds, and was in the first instance so tight as to 
prevent any flow in the field of capillaries supplied by it ; then relaxing slightly, 
it allowed single corpuscles to pass along it with great difficulty, so that the 
blood became almost entirely filtered of its particles, and at the same time the 
force of the heart being to a great extent taken off from the elastic capillaries, 
liquor sanguinis almost destitute of corpuscles flowed in slow pulsating streams 
along the veins: finally, the dilatation becoming complete, blood of ordinary 
appearance rushed through with great rapidity. 
If, however, such experiments had been several times repeated upon the 
same foot, and more especially if the warm water had acted for longer periods, 
another class of symptoms began to show themselves ; the corpuscles passing 
on less freely than the liquor sanguinis through the capillaries, and lagging 
behind so as to accumulate in abnormal proportion to the plasma, and stagnating 
completely when the force of the heart was partially taken off through con- 
traction of the arteries, though passing on again when the vessels dilated.” 
Thus in one case an artery under observation measuring 2° (degrees of the 
* Water of the temperature of the room applied in the same way after warm water had been several 
times employed, caused complete constriction of the arteries, lasting for several seconds ; but the sub- 
sequent dilatation was very little if at all beyond the normal calibre. 
> This effect of arterial contraction in producing accumulation and stagnation of corpuscles in the 
capillaries has been described by Mr. Wharton Jones as occurring in a state of health (see Guy's Hospital 
Reports, loc. cit.). The reason of this I believe to have been, that much greater care than is generally 
supposed is required in order to avoid any irritation whatever of the delicate webs. The vicinity of the 
warm hand is particularly apt to produce this effect ; and I have known it, when continued for a quarter 
of an hour, cause complete stagnation of the blood throughout the webs, while a very much shorter 
period is sufficient to induce a decidedly abnormal condition. I have myself only become fully aware 
of the great susceptibility of the foot of the frog to injury from warmth since the reading of this paper. 
An unhealthy state of the webs is indicated to the naked eye by conspicuousness of the blood-vessels. 
In perfect health they are quite invisible without the microscope, and in all cases the appearance of any 
vessel as a distinct red streak is pretty sure indication of a certain amount of irritation. 
LISTER I Q 
