56 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



The advantage of this method is that the mucin and albuminous 

 materials in the sputum are coagulated and broken up into fine 

 granules by the shaking, and bacilli which occur in small clumps 

 are evenly distributed throughout the film. 



Another method which may be used in difficult cases is to 

 digest the sputum with pepsin and HCl — a pinch of the former 

 and sufficient of the latter to make the fluid faintly acid — in an 

 incubator for a couple of hours, shaking occasionally, and then to 

 boil the digested material to prevent further action. The result 

 may be centrifugalized or allowed to deposit, and the sediment 

 examined. A more recent method is the use of " antiformin," a 

 solution of bleaching powder and caustic alkali. This dissolves all 

 the structures likely to be present in the sputum, except tubercle 

 bacilli. I do not think its use is advisable in ordinary cases. 



Urine may be centrifugalized or allowed to stand without 

 previous addition, but better results are obtained if carbolic acid 

 (liquefied or in crystals) is added to the urine in amount sufficient 

 to convert it into a i in 20 solution. This is allowed to deposit 

 or (better) is centrifugalized. Films are prepared from the deposit. 

 Remember that they should be left in alcohol for a quarter of 

 an hour or so after staining. 



Pus is best carbolized in the same way as sputum ; if very thin 

 it may be treated like urine. The tubercle bacilli will rarely 

 be found in pus unless it is examined soon after the abscess is 

 opened, but may be detected by inoculation experiments for long 

 periods. 



Clear exudates axe more difficult to examine, and, as they usually 

 contain bacilli in very small numbers only, a negative result 

 should not be given too much weight. (For the best method 

 to employ, see section on Cyto-diagnosis, p. 253.) The examina- 

 tion is best made in a bacteriological laboratory, as decisive 

 results can only be obtained by animal experiments. Collect the 

 fluid in a bottle which has previously been boiled in water for 

 half an hour and allowed to cool. Cork it with a cork which has 

 also been boiled. Add no antiseptic, and forward it to the labora- 

 tory as soon as possible. 



Milk may be examined in the same way as urine, films being 

 made from the cream as well as from the deposit. These films 

 are fixed, soaked in ether to remove fat, and again fixed. They 

 are then stained as before, and it is advisable to pass them 

 through alcohol. 



