PREFACE. vii 



apply strict method, and in the place of conjectures to sub- 

 stitute experimental investigations and accurate demonstra- 

 tions. It was this view of the matter which led to both my 

 practical and theoretical investigations. 



The new ideas which I brought forward in my practical 

 studies in fermentation were at first favourably received by a 

 few only of my colleagues, but were, on the contrary, opposed 

 by most of them. I am glad to be able to state here that 

 some of my former opponents may now be counted amongst 

 the most active supporters of my work. I regard this as the 

 greatest tribute which could be paid to it. 



Notwithstanding the success which in different countries 

 attended my endeavours at reform, I had in reality to fight 

 an unbroken battle for its progress ; every step had to be 

 gained by a struggle, and it is this which has to a large 

 extent put a characteristic stamp upon the following re- 

 searches. A great incitement to me in this case, as always, 

 has been the desire to contribute to that literature, the object 

 of which is to prove to the outside world that we in Denmark 

 earnestly take our share of the work of progress, and that, 

 notwithstanding all political reverses, our little nation is still 

 able to develop and carry out independent scientific research. 



In conclusion I have much pleasure in expressing my best 

 thanks to Dr. MILLER for the great interest and care which 

 he has bestowed upon the translation of my work. 



EMIL CHR. HANSEN. 



CARLSBERG LABORATORIUM, COPENHAGEN : 

 June 1895. 



