ON THE ANTISEPTIC SYSTEM 99 



but as slippery as a piece of recent intestine, so that a knot tied upon it yields 

 to the slightest traction. But it is a happy circumstance that a simple process 

 of preparation deprives it of these objectionable qualities. For this purpose, 

 no method which I have yet tried answers better than that which I happened 

 to use first of all for rendering the gut antiseptic — viz. suspending it in a mixture 

 of five parts of some fixed oil (e.g. olive or linseed) with one part of carbolic 

 acid liquefied by adding five per cent, of water to the crystals. Part of the 

 water associated with the acid is disengaged by the oil, producing a very fine 

 emulsion, which effects a remarkable physical change in the animal tissue. 

 At first the gut is rendered swollen, soft, and opaque, though not to so great 

 an extent as if placed in simple water ; but in the course of a few days the 

 opposite change begins to show itself, and the thread becomes gradually firmer 

 and more transparent, till, after the lapse of a few weeks, it is quite free from 

 opacity, and very strong, though supple. If drawn through the fingers, it is 

 no longer slippery, but has a crisp feel like a thread of india-rubber, and a knot 

 tied upon it holds more securely than one on waxed silk. Water, whether cold 

 or at a temperature of 100° Fahr., has now little effect upon the thread, and 

 even putrid serum of blood acting upon it for days at the temperature of the 

 body does not make the knots relax their hold. In this form the gut seems 

 almost a perfect material for the ligature under any circumstances in which it 

 is required. 



' Prepared catgut ' will, I hope, soon become a well-known article of com- 

 merce. But, for the sake of surgeons who may wish to prepare it for them- 

 selves, it is necessary to mention, in order to avoid disappointment, that the 

 essence of the process is the action of an emulsion of water and oil upon the 

 animal tissue. The same effect is produced upon the gut, though more slowly, 

 by an emulsion formed by shaking up simple olive oil and water, as b\^ one 

 which contains carbolic acid. On the other hand, an oilv solution of carbolic 

 acid without water has no effect upon the gut beyond making it antiseptic, 

 and if water be added only in the small proportion which the acid enables the oil 

 to dissolve, though the gut is rendered supple, and acquires a dark tint from the 

 colouring matter of the oil, it will be found, even after steeping for months in 

 such a solution, that when transferred to water it swells up and becomes soft, 

 opaque, and slippery, as if it had not been subjected to any preparation. How 

 it is that an emulsion produces this remarkable change in the molecular con- 

 stitution of the tissue I do not profess to understand. I was at first incHned 

 to regard it as a closer aggregation of the particles, brought about b}' a kind of 

 slow drying of the moistened gut in the oil, as the watery particles precipitate to 

 the bottom of the vessel ; but, not to mention other circumstances opposed 



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