vi BIOLOGICAL CHEMISTRY 



namely that of Friedemann in the Handbuch der 

 Hygiene (3rd vol. 1st part, p. 777, 19 13). " The one- 

 sided (ausschliesslick) interest which has been 

 directed to this problem ' (the neutralization of 

 antigens and antibodies) " is not justified by its 

 biological importance." Yet I am convinced that 

 biological chemistry cannot develop into a real 

 science without the aid of the exact methods offered 

 by physical chemistry. The aversion shown by bio- 

 chemists, who have in most cases a medical education, 

 to exact methods is very easily understood. They 

 are not acquainted with such elementary notions as 

 " experimental errors," "probable errors," and so 

 forth, which are necessary for drawing valid con- 

 clusions from experiments. The physical chemists 

 have found that the biochemical theories, which are 

 still accepted in medical circles, are founded on an 

 absolutely unreliable basis and must be replaced by 

 other notions agreeing with the fundamental laws of 

 general chemistry. 



I was very glad to find on my last visit to 

 England that interest in an exact treatment of bio- 

 chemistry is rapidly growing, and therefore I received 

 with great satisfaction the proposal of Messrs. G. 

 Bell & Sons to publish a book founded on the 

 Tyndall lectures given by me in the Royal Institu- 

 tion in May 19 14. They contain a short resume of 

 my own work in this field, supplemented by the in- 

 vestigations of others on neighbouring ground. 



The reader who wishes to consult the literature 

 of the subject will find references in : 



