INTRODUCTION 
XXXVI1I 
less slender threads of organic material, prepared so as to be free from septic 
organisms, might be similarly removed. 
Lister’s experiments and observations on this subject are fully recorded in 
papers printed in volume ii. He first, on the 12th of December, 1867, tied 
the left carotid artery of a horse with purse-silk which had been steeped in a 
strong watery solution of carbolic acid ;' the ends were cut short, and the wound, 
which was dressed antiseptically, healed immediately. Six weeks later the horse 
died, and on laying open the vessel there was found at the cardiac side of the 
ligature a firm adherent clot, an inch and a quarter long, but at the distal side 
coagulation had been entirely prevented by the reflux current of blood through 
a branch about as large as the human vertebral artery, which took origin as close 
to the ligature as possible. Under such circumstances secondary haemorrhage 
would certainly have occurred had a thread been applied in the manner then 
commonly employed. But in this specimen the artery appeared as strong at 
the part tied as elsewhere. The cul-de-sac showed some irregularity due to 
puckering of the internal and middle coats, but the surface appeared completely 
cicatrized, and presented the same character as the natural lining membrane 
of the vessel, and the ligature, which seemed as yet unaltered, was found lying 
dry in a bed of firm tissue. The tissue within the noose was apparently a new 
formation in place of the portion of external coat killed by the tightly tied 
thread ; externally, the constriction, necessarily caused in the first instance by 
tying the ligature, had been filled in by a similar compact structure. 
The success of this experiment justified the application to man of the 
principle upon which it was based. Accordingly, when a few weeks later (29th of 
January, 1868) Lister was called upon to tie the external iliac artery for aneurysm 
of the common femoral artery in an elderly lady, he made use of a silk ligature 
steeped in undiluted carbolic acid, used sufficient force to divide the inteinal 
and middle coats of the artery, cut the ends of the ligature short, and dressed 
the wound antiseptically. The aneurysm consolidated, the wound healed without 
suppuration, and the patient was out of bed in four weeks, and was able to take 
outdoor exercise in two more. Within a year she died suddenly from rupture 
of an aortic aneurysm. Careful examination of the iliac artery after death 
showed that the knot of silk was still in great part present, enclosed in a thin- 
walled capsule. Besides the remnant of the ligature, the tiny capsule contained 
a minute quantity of yellowish semi-fluid material, looking to the naked eye 
very like thick pus. Microscopic exaniination, however, proved that pus cor- 
puscles formed but a small proportion of its constituents, which were princi- 
pally rounded corpuscles of smaller size, and fibro-plastic corpuscles, together 
* Vol. i, p. 64. 
