Lord Lister. 



IX 



cent, of carbolic acid surrounded the wound during the operation and at each 

 subsequent dressing. The idea was that the fine particles of the spray 

 coining in contact with the bacteria floating in the atmosphere would kill 

 them before they fell into the wound, while at the same time only a small 

 amount of carbolic acid would come in contact with the wound and so the 

 local irritation by the carbolic acid and the amount of absorption would be 

 very much less than by the former plan. 



With the view of preventing irritation of the line of incision by the 

 carbolic acid contained in the discharges, many experiments were made to 

 find some material which could be interposed between the dressing and the 

 line of incision, and which would be impermeable to carbolic acid. 

 Ultimately a satisfactory " protective " was obtained by covering the ordinary 

 oil-silk used for surgical purposes by a layer of copal varnish. The surface 

 of this prepared oil-silk was then painted over with a layer of dextrine and 

 starch, so that when placed in carbolic lotion in order to disinfect it, it should 

 be wetted all over. A narrow strip of this " protective " was laid over the 

 line of incision before the gauze dressing was applied. 



While Lister was thus engaged in improving his methods for destroying 

 bacteria and preventing their access in a living state to wounds, he also spent 

 much time in improvements in the treatment of wounds apart from the 

 question of asepsis. The most important of these improvements was the 

 introduction of absorbable ligatures. Up to the time when he commenced 

 his great work the blood vessels were tied with silk or hemp, and as 

 these ligatures had to separate by ulceration and suppuration before the 

 wound could heal, they were left long and hung out of the wound in bundles, 

 so that they could be pulled out when they became loose, usually about the 

 eighth or tenth day after the operation. As the result of the prevention of 

 suppuration, one of the first things observed was that these ligatures did not 

 separate and there was much trouble in getting rid of them ; in fact they 

 sometimes had to be cut short and left in the wound. 



Lister accordingly turned his attention to this matter and made many 

 experiments in order to see what happened to the ligature in aseptic wounds, 

 and whether it might not be cut short and the wound closed over it. He 

 •found that this was the case and that silk ligatures might be cut short and 

 left without causing any trouble. On examining these ligatures after they 

 had been buried in the tissues for some months he found that they were 

 undergoing destruction and that the threads of the silk were being broken up 

 and absorbed by the cells of the body. The process was, however, a very slow 

 one and after more than a year considerable fragments of the silk were still 

 present. He therefore looked for some material which would be suitable for 

 ligatures and which would be more quickly absorbed, and tried various animal 

 substances, ultimately concentrating his attention on catgut. (Although 

 Lister was not aware of it, catgut had been tried as a ligature material many 

 years previously, but discarded as quite unsuitable. At that time the wounds 

 were septic and the catgut was extruded from the wounds just as silk was, 



