140 THE KINGDOM OF MAN 



sensitisers and opsonins to paralyse and prepare their 

 bacterial food. And the experiments of MetschnikofFs 

 pupils and followers show that this is undoubtedly the 

 case. Whether there is any great variety of and differ- 

 ence between ' sensitisers ' and ' opsonins ' is a matter 

 which is still the subject of active experiment. Metschni- 

 koffs conclusion, as recently stated in regard to the whole 

 progress of this subject, is that the phagocytes in our 

 bodies should be stimulated in their activity in order 

 successfully to fight the germs of infection. Alcohol, 

 opium, and even quinine, hinder the phagocytic action ; 

 they should therefore be entirely eschewed or used only 

 with great caution where their other and valuable pro- 

 perties are urgently needed. It appears that the injection 

 of blood-serum into the tissues of animals causes an 

 increase in the number and activity of the phagocytes, 

 and thus an increase in their resistance towards patho- 

 genic germs. Thus Durham (who was a pioneer in his 

 observations on the curious phenomena of the 'agglu- 

 tination ' of blood corpuscles in relation to disease) was 

 led to suggest the injection of sera during surgical 

 operations, and experiments recently quoted by Metschni- 

 koff seem to show that the suggestion was well founded. 

 Both German and French surgeons have employed the 

 method with successful results, and the demonstration 

 that an immense number of microbes are thus taken up 

 and destroyed by the multiplication (due to their regular 

 increase by cell-division) of the phagocytes of the 

 injected patient. After years of opposition bravely 

 met in the pure scientific spirit of renewed experiment 

 and demonstration, Metschnikoff is at last able to say 

 that the foundation-stone of the hygiene of the tissues 

 the thesis that our phagocytes are our arms of defence 

 against infective germs has been generally accepted. 



