6 Sir Everard Home on the conversion of Pus 
this was of so transparent a nature, that a number of small 
bubbles of gas were seen to make their appearance in dif- 
ferent places ; in a few minutes more, horizontal canals of 
different sizes, filled with red blood, taking different direc- 
tions, and anastomosing with one another, were seen to form. 
In some places, there were red points, the terminations of 
perpendicular canals, that had been stopped in their course, 
by coming against the pellicle. There were also occasional 
specks of extravasation, from some of the horizontal canals 
bursting through the pellicle.* 
The changes just mentioned seemed to occur in a regular 
order of succession. First, the pellicle was formed on the 
surface. Secondly, the bubbles of gas made their appearance. 
Thirdly, the canals carrying red blood were observed : 
these, while filled with carbonic acid gas, were not to be 
distinguished from the semi-transparent jelly which sur- 
rounded them. 
As it is difficult to describe appearances of this kind, and 
it is of importance that the fact of such appearances being 
met with, should be well established, I requested Mr. Bauer 
to make a drawing of a portion of the sore of which I have 
attempted a description, after it had been exposed for nearly 
sixteen minutes ; and on the following day he made a draw- 
ing of the same portion, showing the progress that had been 
made, and that the canals formed on the first day, had on the 
second become permanent tubes, and had been covered over 
by a cuticle. These two drawings are annexed. 
* If, under these circumstances, the foot was put to the ground, so weak was the 
covering of the canals, that it instantly gave way, and the sore was covered with 
blood. 
