LIFE OF ELIE METCHNIKOFF 149 



attacked it, trying to prove that phagocytes played 

 no part in immunity, which, according to him, 

 depended upon the chemical properties of the blood. 



Soon after that, Behring discovered antitoxins, 

 and this seemed to favour the chemical or humoral 

 theory of immunity. According to the latter, microbes 

 and their poisons were rendered harmless by the 

 chemical properties of the blood serum, properties 

 similar to those of disinfecting substances. 



In spite of his firm conviction of the solidity of the 

 phagocyte theory, this discovery was a shock to 

 Metchnikoff, for it was in apparent contradiction with 

 the cellular theory of immunity. He hastened to 

 undertake a series of researches ; his overflowing 

 eagerness infected his whole circle, every one taking 

 the warmest interest in the progress of his experi- 

 ments. 



This was just as preparations were being made to 

 take part in the London Congress, where the question 

 of immunity was to be debated and had indeed been 

 placed at the head of the programme. Many papers 

 were being prepared, and a veritable tourney of 

 opinions was to take place at this Congress. 



Metchnikoff had already been to England once, 

 in the spring of 1891, on the occasion of his reception 

 as an Honorary Doctor by the University of Cam- 

 bridge. This gave him the opportunity of making 

 closer acquaintance with the English, who inspired 

 him with great sympathy ; years only increased this 

 feeling. He appreciated the originality of their 

 earnest and generalising spirit, their loyalty and 

 energy ; he was grateful to them for the attentive 

 and favourable attitude with which his scientific 

 work and himself had been received. 



