PRODUCED BY ALCOHOLIC FERMENTS. 183 



This was the universal standpoint in 1884. The researches 

 which I published in the course of the following year, and the 

 results thereby achieved in the fermentation industry, caused 

 Thausing's doubts to disappear, and in the third edition of 

 his famous handbook on the manufacture of beer, he gave me 

 full credit for my system of pure yeast culture. 



We have now reached the end of this historical review. 

 The following part of this chapter will deal with the investiga- 

 tions concerning the diseases of beer which I have carried out 

 since 1881. Several investigations which have had an indirect 

 bearing on the development of the doctrine of the diseases of 

 fermented liquors are only briefly touched on, whilst others 

 are not mentioned at all. Amongst these are especially such 

 as treat of the diseases of plants which are brought about by 

 fungi, and contagious diseases in man and animals produced 

 by bacteria. Experimental investigations in the former 

 direction were undertaken as early as the beginning of this 

 century, and the Dane, Scholer, may be named as a pioneer 

 of that time. Advance was likewise also slow in this field, 

 but it continually brought greater clearness. In more recent 

 times the Danish botanists, A. S. Orsted and E. Rostrup, 

 have been conspicuous, whilst the names of Tulasne and De 

 Bary are especially famous in this field. 



Even in the writings of Linne and several of his contem- 

 poraries we find the idea expressed that fermentation, putre- 

 faction and contagious diseases are caused by microscopic 

 organisms. In the year 1840, Henle showed, with great 

 acuteness, that known facts and observations indicate that 

 contagious diseases must be attributed to the attack of micro- 

 scopic organisms. It was, however, only in more recent times 

 that experimental proofs were forthcoming, and it was then 

 that Pasteur's investigations brought him his greatest fame. 



The young science of micro-organisms has developed in 

 all essential particulars from the much older science relating 

 to the higher forms of plants and animals. Just as biology 



