2l8 MANUAL OF BACTERIOLOGY. 



a heavy retaining suture, and is prepared by washing the 

 strands in ether to free from fat. Soak in a 4 per cent, solu- 

 tion of chromic acid for twenty-four hours. Then sterilize 

 by the cumol method. 



Silk may be sterilized by the fractional method (see p. 63) 

 as this does not impair the strength as does boiling. 



Silkworm gut is prepared by steam sterilization by the 

 fractional method or by boiling in plain water for one half 

 hour. It should not be boiled in soda solution as this spoils 

 the gut. 



Horsehair strands are cut into two-foot lengths, washed 

 with soap and water and sterilized with steam by the frac- 

 tional method. They make a very fine suture and are 

 used where an inconspicuous scar is particularly desirable, 

 as on the face. Only the finer grades are used for this 

 purpose. 



Silver Ti'/'/T. 1 This material has the advantage over other 

 suture materials of having a germicidal or at least a restrain- 

 ing influence on bacteria. If we remember that absolute 

 sterilization of the skin is not possible by any means, we 

 must see that in silver wire as a skin suture we have a safe 

 and valuable material. Recent annealing by heating to a 

 dull red increases the flexibility of the wire but almost 

 totally destroys its germicidal property. This will reappear 

 in a month and is not disturbed by boiling. Therefore pre- 

 pare it by boiling for ten minutes in the I per cent, soda 

 solution. 



Sponges. The best absorbents to use in surgical work are 

 those whose sterility is undoubted. Pads of gauze are easily 

 sterilized by steam as for dressings. Sea sponges 2 may be 

 prepared by beating with a wooden mallet to remove sand 

 and dirt. Soak in a 1-64 solution of hydrochloric acid for 



1 Bolton, Transactions Association American Physicians, 1894. 

 " McBurney, "International Text-Book of Surgery/' June, 1900, p. 

 284. 



