INFECTION AND RESISTANCE 



the parallelism between opsonic index and: clinical condition was 

 founded. 



Wright's own earlier studies were made chiefly upon staphylococ- 

 cus infections and tuberculosis. Since then the method has been 

 applied to almost all known infections with varyingly successful 

 results. 



One of the first steps in determining such a parallelism between 

 the resistance of a patient and the opsonic index consisted, of course, 

 in comparing the index of the sera of normal individuals with that 

 of patients suffering from infection. Wright and Douglas did this 

 in a large series of studies. In the case of staphylococcus infections 

 the following experiment will illustrate their results: 



TABLE I 



(Wright and Douglas, Proc. Royal Soc., Vol. 74, 1904.) 

 Showing the ratio in which the phagocytic or opsonic power of the 

 patient's blood stood in each case to the phagocytic or opsonic power of the 

 normal individual who furnished the control blood. (The phagocytic power 

 of the control blood is taken in each case as unity.) 



In this series, as in others investigated by Wright and his col- 

 laborators, staphylococcus infection was uniformly associated with 

 a low index. He concludes that there is probably a causative rela- 

 tion between the two facts, in that under conditions of depressed 

 phagocytic powers staphylococci may gain a foothold, while under 



