ACCLIMATISATION HYPOTHESIS 111 



their existence, and this theory is capable of receiving 

 support from various experimental facts. 



It is on this hypothesis, and the theory of acclimatisation, 

 that the antitoxin treatments which are just now receiving 

 so much attention are based. By antitoxin treatment we 

 endeavour to arm the body against the growth of the specified 

 organisms or the formation of their metabolic products, by 

 putting into it, ready-made, those products that would be 

 produced naturally in convalescence, and by their action 

 would bring the disease to a successful termination. 



Acclimatisation Hypothesis. — According to this hypothesis, 

 it is assumed that the cells of the body become used to the 

 products of the organisms, and that at last they cease to 

 have any injurious influence on them. From analogy this 

 seems a tenable theory, as we see in both the animal and 

 vegetable kingdoms numerous examples of successful accli- 

 matisation. 



The Phagocyte Hypothesis. — This hypothesis was first 

 put forward by Metschnikoff, who when experimenting with 

 virulent anthrax bacilli on frogs, which are normally insus- 

 ceptible to anthrax, found that the white corpuscles put 

 out two processes to surround the bacilli, which were 

 ultimately absorbed in the centre of the corpuscle. 



He also held that if in the case of a local infection the 

 first number of leucocytes that hurried to the spot were not 

 sufficient to repel the invaders, more and more were brought 

 forward, till at last they were so numerous that the 

 organisms could not make any headway, and were thus 

 destroyed. The attraction possessed by living or dead 

 bacteria for the leucocytes is remarkable, while they are 

 equally repelled by the presence of certain bodies, such as 

 quinine, chloroform, etc. 



The term chemiotaxis has been applied to this pheno- 

 menon ; when the leucocyte is attracted towards a body, the 



