120 BACTERIOLOGICAL DIAGNOSIS. 



Where possible it is preferable to apply a dressing of 

 lint soaked in one of the above lotions (which need be 

 of only half the strength) for a few hours. 



The puncture may be made by means of some sort of 

 exploring syringe, or by means of a hollow needle with- 

 out any means for aspiration. The former is used for 

 the removal of fluid from the pleura or synovial cavity, 

 the latter in performing lumbar puncture. But it is 

 necessary that the whole of the instrument used should 

 be rendered sterile by heat ; chemical antiseptics are 

 quite inadmissible. In the case of a hollow needle no 

 difficulty occurs ; some hypodermic syringes, however, 

 will not stand boiling, and these are useless for the 

 purpose, as the apparatus which is to be used must be 

 boiled for at least five minutes. 



We shall now deal with the most important cavities 

 of the body, describing the methods to be employed in 

 the investigation of the inflammatory exudates which 

 they may contain, and the inferences which may be 

 drawn from the results of the examination. 



THE PLEURA. 



There is but little to be said about the method to be 

 employed in the collection of fluid from the pleural 

 cavities. The most careful antiseptic precautions are 

 to be taken, and the region to be punctured should be 

 decided by consideration of the physical signs. 



The examination of the fluid thus obtained may be 

 either microscopical, cultural, or by injections into 

 animals. If the latter are required (and inoculation 

 should be performed in all cases where a tubercular 



