PATHOLOGICAL EXUDATES. 



and cord, and the joints. In some cases all the needful 

 information may be obtained by the examination of 

 stained films, cultures being unnecessary ; and in these 

 cases no anti- or aseptic precautions (other than those 

 which are dictated by the interests of the patient) are 

 necessary. But in the greater proportion of cases this 

 is not enough, and cultures must be obtained. To this 

 end it is absolutely essential that the most scrupulous pre- 

 cautions should be taken against contamination of the 

 fluid by the organisms which are constantly present in 

 the air and in the skin, or the results will be worthless. 

 The precautions taken must be as complete as those 

 which are used before an operation upon a joint. 

 Indeed, a fresh precaution has to be taken, for whereas 

 the presence in the skin of a small quantity of an anti- 

 septic would not be detrimental to a surgical operation, 

 it might, by getting into the fluid, nullify a bacterio- 

 logical examination. Hence the skin must be aseptic 

 and free from any antiseptic chemical. 



The technique, as far as aseptic precautions are con- 

 cerned, is as follows : The skin at the region to be 

 punctured is first thoroughly cleaned with soap, hot 

 water, and (if the patient can stand it) a nailbrush. 

 Then layer after layer of some reliable antiseptic lotion 

 is painted on, each layer being allowed to soak in before 

 the next is applied. The most suitable lotions for the 

 purpose are perchloride of mercury (i in 1000) biniodide 

 of mercury, (i in 500 of methylated spirit) or carbolic 

 acid (i in 20). 



After being allowed to act for at least ten minutes 

 the skin is to be thoroughly cleansed with methylated 

 spirit ; this should be rubbed in with a piece of cotton- 

 wool and should be poured copiously over the area. 

 The operation may now proceed. 



