8 T. P. ANDERSON STUART. 



The Opsonin Treatment.— As you know, the mode of 

 dealing with disease germs so as to avoid the disease to 

 which they give rise has been to keep them and us apart 

 — to keep our bodies away from infective sources, and to 

 keep sources of infection away from our bodies. But do 

 what we will, somehow or other disease germs reach us 

 more or less frequently, and in greater or less numbers, so 

 that absolute protection pure and simple is a hopeless task. 

 An entirely new way of looking at the subject has gradually 

 been gaining ground during the past few years, and 

 especially in the past year or two it may be regarded as 

 established. It is due to the genius of Metschnikoff, who 

 showed that certain colourless cells of the blood can and 

 do devour and destroy the invading organisms, and so pre- 

 vent their growth and multiplication. In short, they 

 absolutely combat the disease producers. These cells 

 Metschnikoff called " phagocytes." If the invading organ- 

 ism is too much, too numerous or too strong, for the 

 phagocytes, then these latter are overcome, the disease 

 germs get the upper hand, and an attack of the disease is 

 produced. 



Sir Almroth Edward Wright, formerly for some years 

 connected with the University of Sydney as Demonstrator of 

 Physiology, is mainly responsible for the discovery that in 

 the struggle between phagocytes and microbes, the microbes 

 are rendered more palatable, or at least more readily 

 devoured and destroyed by the phagocytes, by the presence 

 of certain substances which he named "opsonins," and 

 which are produced either by the tissues themselves or by 

 the phagocytes. For each kind of microbe there are specific 

 kt opsonins," the presence of which in increased quantities 

 in the blood is secured by injecting the microbe itself into 

 the blood. This word " opsonin " is from the Greek word 

 "opson," meaning a seasoning or sauce. After the 



