The Washed Leukocytes 283 



always followed by a temporary diminution (negative phase) 

 of the opsonic index, soon followed, if the dose be not 

 too large, by a marked increase (positive phase). It is sup- 

 posed, upon theoretical grounds, and proved by practical 

 experience, that the increase of phagocytic activity brings 

 about improvement. The care of the operator should be 

 to avoid giving so large a dose of the vaccine that the 

 negative phase will be so long continued that harm instead 

 of good may be achieved. 



The study of the opsonins has been industriously pursued, 

 chiefly in the English- speaking countries, and although 

 there is some doubt about the actual significance of the 

 counts in relation to the immunity of the patient, it is agreed 

 that the method is an advance upon all past methods of 

 forming judgment in such cases. 



