DIAGNOSTIC APPLICATIONS OF THE BLOOD-COUNT 287 



test, similar in general terms to the Wassermann reaction for 

 syphilis, which appears to give satisfactory results. The 

 antigen used is hydatid fluid from a previous case. 



PERITONITIS AND APPENDICITIS. See p. 279, Sepsis and 

 Suppuration. 



PLEURISY AND EMPYEMA. With a mechanical pleural 

 effusion (cardiac or renal) there is no leucocytosis. With 

 simple non-tuberculous pleurisy the blood is usually normal, 

 and the same holds in the tuberculous cases, but here the 

 leucocytes are occasionally raised to 18,000 or more. Such 

 cases may be distinguished from pneumonia or empyema by 

 the presence of the iodine reaction in the latter and its 

 absence in pleurisy. Empyemata are associated with a high 

 leucocytosis, except sometimes in the tuberculous forms. 



ASTHMA. True asthma has a very characteristic blood con- 

 dition. During" an attack there is a leucocytosis of moderate 

 grade, with a great increase of eosinophiles ; 10 per cent, may 

 be taken as an average, though much higher counts have been 

 recorded. In the intervals the total numbers are normal, but 

 there is usually a moderate eosinophilia, 5 to 7 per cent, or 

 more, and I have found a slight increase of mast cells (about 

 i per cent.), which is so rare a phenomenon that it may be of 

 some diagnostic value. Eosinophilia rarely occurs associated 

 with other forms of spasmodic dyspnoea, and its presence 

 serves to diagnose asthma from cardiac or renal dyspnoea 

 often a matter of g'reat importance or from dyspnoea due to 

 pressure on the bronchi, trachea, etc. 



The sputum in asthma is usually characteristic, and contains 

 the peculiar spirals and vast numbers of eosinophile cells; 

 these are rarely seen in cases of bronchitis, but never in any 

 numbers in other diseases. 



BRONCHITIS AND BRONCHO-PNEUMONIA. With simple bron- 

 chitis there is the usual inflammatory leucocytosis, usually 

 about 12,000 to 14,000. In broncho-pneumonia the count is 

 much higher 20,000 or more. This applies to children as 

 well as to adults. 



ENDOCARDITIS. Not much help can be obtained from the 

 leucocytes in the diagnosis between the simple and the 

 malignant form, since in either case there may be a normal or 

 slightly raised count. But in malignant endocarditis there is 

 usually a rapidly increasing anaemia of secondary type. The 



