158 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



uselessness of an operation) in cases of lateral sinus thrombosis 

 and cerebral abscess. The fluid usually becomes bloody within 

 twenty-four hours of a fracture of the base of the skull or lacera- 

 tion of the brain. This may assist in the diagnosis of obscure 

 injuries, or of the cause of a case of unconsciousness in which no 

 history can be obtained. 



Heemorrhage into the meninges is indicated by the withdrawal 

 of blood-stained fluid, but it must be remembered that the first few 

 drops may contain a small quantity of blood which has entered 

 the needle during its passage through the tissues, while the rest 

 is clear. When blood from a vein injured by the needle is mixed 

 with cerebro-spinal fluid, coagulation usually occurs if the fluid is 

 allowed to stand, whereas when the blood comes from a haemor- 

 rhage this is not usually the case. Blood-stained fluid may occur 

 in meningitis, and should be submitted to a full examination for 

 leucocytes and bacteria. 



THE BACTERIOLOGICAL EXAMINATION OF 

 THE BLOOD 



The bacteriological examination of the blood is not so important 

 as might be thought, as it is only in comparatively few diseases 

 that pathogenic bacteria are present in the circulation in such 

 quantities as to render the search for them in the relatively small 

 amounts which are withdrawn for examination at all promising. 

 The method is becoming of more importance daily, since promis- 

 ing results have been obtained in the treatment of septicsemic 

 diseases by means' of specific vaccines, which, to get the full 

 advantage of the process, should be obtained from cultures of the 

 patient's own bacteria. 



The chief organisms which have been found in the blood are : 

 I and 2. Streptococci and Staphylococci. — These are found in cases 

 of septicasmia, pyaemia, ulcerative endocarditis, etc. ; they indicate 

 an extremely bad prognosis, though the use of vaccines has now 

 improved matters somewhat in this respect. The chief importance 

 which attaches to the discovery of these organisms is that it 

 absolutely settles the diagnosis (always provided that there are 

 no errors in technique), and that it indicates whether the use of 

 a vaccine or antistreptococcic serum is advisable or not ; it is 

 useless in cases of septicaemia, etc., which are not due to strepto- 

 cocci. 



