142 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



precaution is not taken the iodine sometimes causes a transient, 

 but annoying, dermatitis. 



The puncture may be made by using some sort of exploring 

 syringe, or a hollow needle without 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 as a rule 

 inadmissible. In the case of a hollow needle no difificulty occurs ; 

 some hypodermic syringes, however, will not stand boiling, and 

 these are useless for that 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 infer- 

 ences 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 tuberculous origin is suspected) a considerable 

 quantity of the fluid — an ounce or more — should be enclosed in 

 a bottle which has been sterilized by boiling, and forwarded at 

 once. A drachm or more of lo per cent, sodium citrate solution 

 (boiled) should be added to prevent coagulation. 



Where the diagnosis is to be made by cultural methods, and 

 the cultures are not to be made on the spot, the fluid is best 

 stored or sent to a laboratory in pipettes. These are to be filled 

 from the syringe direct ; the needle is to be removed, and the end 

 of the pipette (sterilized by being passed through the flame) is 

 passed into the fluid, and filled by gentle suction at the other end. 

 Each end is then sealed in a flame, care being taken not to heat 

 the fluid. Two or three such tubes should be sent. 



Clear fluid from the chest rarely shows any micro-organisms on 

 microscopical examination. Cultures are usually sterile ; where 



