XXXVI INTRODUCTION 
with some imperfect fibres and granular material. There were evidences of the 
silk having been eroded by the action of the tissues around it, pieces of its fibres 
being present in the puriform fluid ; they had not been materially softened, but 
only ‘ superficially nibbled, so to speak. Indeed,’ Lister added, ‘ considering the 
organic character of silk, the remarkable thing seems to be, not that it should be 
absorbed by the living tissues, but that it should resist their influence so long.’ 
The local result in this case was thus not altogether satisfactory, and Lister 
therefore turned his attention to other materials. Animal ligatures of various 
kinds, catgut, tendon, and leather, had long before been tried and abandoned 
as unsatisfactory, but there was good reason to expect that in the absence of 
sepsis very different results would ensue. Lister had been struck by the fact 
that the sloughs and clots produced by the injection into naevi of strong solutions 
of perchloride of iron or tannic acid, though impregnated with these substances, 
yet rapidly disappeared without suppuration. He had also learnt that portions 
of dead tissue and of blood-clot, free from sepsis, were absorbed, and that this 
process was in no way interfered with when carbolic acid had freely acted upon 
them. There seemed, therefore, to be no reason why carbolic acid should not 
be used for disinfecting the animal ligature. 
In his next experiment, in which (on the 31st of December, 1868) he tied 
the right carotid of a calf at about the middle of the neck, he applied two ligatures 
separated from each other by a distance of about an inch and a half. One was 
composed of three strips of peritoneum from the small intestine of an ox, twisted 
into a cord, the other was of fine catgut. Both had previously been soaked for 
four hours in a saturated watery solution of carbolic acid. The wound healed by 
first intention, and the calf was killed a month afterwards. The result of the 
dissection of the vessel was at first disappointing, for the ligatures were still to 
all appearance present and as large as ever ; more minute examination showed 
that in reality they had been absorbed and replaced by bands of living tissue, 
‘the growing elements of which had replaced the materials absorbed, so as to 
constitute a living solid of the same form’. The fleshy bands so formed were 
continuous with the arterial walls, and so far from weakening the vessel at the 
point of ligature had rather strengthened and reinforced it, while by the early 
healing of the wound an immediate reconsolidation of the tissues detached from 
the vessel had taken place. The evidence of the organization of the ligatures, 
clear to the naked eye, was abundantly confirmed by the microscope. All these 
facts seemed to give sure promise, as indeed has proved to be the case, of security 
against secondary haemorrhage, so frequent and so justly dreaded up to that 
time, as well as of the absence of suppuration in connexion with such 
ligatures. 
