PRODUCED BY ALCOHOLIC FERMENTS. 179 



considers that this may quickly disappear on cultivation, or 

 that it may become changed into quite a different function. 

 According to Nageli neither the morphological nor the 

 physiological forms are constant, but readily merge into one 

 another. The chemical composition of the substratum and 

 the external conditions form important active factors which 

 bring about transformations in various directions. Nageli's 

 standpoint with regard to the idea of species is difficult to 

 understand, and, as already stated, he gives no experimental 

 proof for the different cases. Jn his ' Theorie der Gahrung,' 

 1879, p. 1 20, he also expresses a similar view. 



In his zymotechnic retrospect of the year 1877,* Holzner 

 pointed out that the investigations hitherto conducted gave 

 brewers no reliable information with regard to the irregu- 

 larities which so often occur in the fermentation, and he refers 

 especially to the confusion which prevails with regard to the 

 species of yeast Some regard each form as a special species. 

 According to others, the different species readily change one 

 into another. We are here confronted with enigmas and pro- 

 blems which still remain unexplained. With regret he points 

 out that " hitherto the number of hypotheses regarding fer- 

 mentation and the morphology, biology and physiology of the 

 fermentation fungi (and ferments) has not diminished but has 

 continually increased." And he refers to his famous countryman, 

 Nageli, as one likely to help in throwing light on the subject 



On looking through the various brewing journals of 

 the period to which we are now referring, it will be found 

 that they contained frequent complaints of disturbances and 

 irregularities in the fermentation, and of difficulties and 

 losses caused by diseases of the beer. A similar complaint 

 occurs in a paper by C. Lintner, sen.,f in which he points to 



* Holzner, "Zymotechn. RiickLlicke auf das Jahr 1877,'' ' Zeitschr. f. das ges. 

 Brauwesen,' Munich, 1878, p. 142. 



t C. Lintner, sen., " Ueber Malz und dessen Einfluss auf die Haltbarkeit und 

 Giite des Bieres," ' Zeitschr. f. das ges. Brauwesen,' Munich, ifcSo, p. 384. 



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