ON THE EARLY STAGES OF INFLAMMATION 227 
From the facts above mentioned, I became convinced that no satisfactory 
explanation had as yet been given of the obstruction experienced by the blood- 
corpuscles in the vessels of an inflamed part, and in September 1856, I again 
continued the investigation. Mustard being admitted to produce inflammation 
in any part of the human body to which it is applied, and also not appearing 
likely to act by way of exosmose, I selected it as a suitable irritant, and in order 
to study its effects accurately, placed a small portion of its moistened flour, 
about a line in diameter, upon the middle of the web of a large frog under chloro- 
form. After a while, thinking that I saw stagnation in a capillary just at the 
margin of the mustard, I removed the latter with a camel’s-hair brush, and 
was surprised to find that throughout the whole area on which it had lain, the 
capillaries were crammed with either stagnant or very slowly moving red cor- 
puscles. The limits of the part so affected corresponded exactly with the extent 
of the application of the mustard, although the capillaries of adjoining parts 
were fed and drained by the same arteries and veins, 
On the 3rd of October I made another similar experiment, selecting a part of 
the web where a considerable artery divided into small branches. Before applying 
the irritant, I had ascertained that the artery running through the area measured 
64° of an eyepiece-micrometer,! while a large vein near it had a diameter of 12°. 
About half a minute after the application of the mustard, when I first looked 
through the microscope, the arteries of the web generally were much dilated, 
and the flow, which had before been somewhat languid, was rapid in all its 
the capillaries, and that the liquor sanguinis being consequently inspissated, the red corpuscles assumed 
an abnormal tendency to aggregate together (see Guy’s Hospital Reports, loc. cit., p. 40). This view 
has been more recently advocated by a German writer, Fr. Schuler of Glarus (Wiirzburg Verhandlungen, 
1854), with a very elaborate series of difficult experiments. One of these, however, seems almost con- 
clusive against his theory. Having injected a solution of prussiate of potash into the veins of a frog, 
he applied sulphate of iron to the webs, but found that very little blue colour was produced unézl the 
epidermis of the web was scraped away, when it showed itself distinctly. Considering how delicate a test 
prussian blue is of the presence of a mixture of the two salts, this result seems to show that there is far 
from being the same tendency to mutual interchange between the blood in the capillaries and fluids in 
contact with the surface of the web, as there would be if the intervening material were dead animal 
membrane of the same tenuity. Were the disposition to exosmosis and endosmosis such as is assumed 
in the above explanation of stasis from a solution of salt, it would be impossible for the animal to live 
long either in water or on dry earth. In the former case the blood would soon become diluted from 
imbibition, and in the latter inspissated from evaporation. But it is well known that frogs will live for 
months in water without food, and I have kept them for weeks together upon dry earth at a temperature 
of about 60° Fahr., and on removing from the webs a layer of dust and exfoliated epidermis, found the 
circulation perfectly healthy. Since the reading of this paper, I have seen a remarkable example of 
the power of the tissues of the webs to resist imbibition of water in an amputated limb with the blood 
retained in the vessels by a ligature. Though it was kept in wet lint, the blood in the vessels showed 
no indication of admixture of water till the tenth day, and then only in those parts of the web in which 
the arteries and pigment-cells gave evidence that they had lost their vitality. For further particulars 
regarding this experiment see pp. 39 and 63 of this volume. 
+ The micrometer used on this occasion was differently graduated from that employed in the warm- 
water experiments. 
Q 2 
