io PURE CULTURES OF 



himself has also claimed the priority of the gelatine method, 

 the honour of which we are accustomed to attribute, and 

 justly, to Koch. Brefeld's methods were elaborated with 

 regard to morphological researches, especially of mould fungi, 

 and for that purpose they are good ; whilst they are unsuited 

 for producing mass-cultures of bacteria and yeast cells (see 

 Holm's above-named treatise, and Brefeld's publications, 

 quoted therein). 



Whatever method of pure culture we may employ, it is 

 and remains nothing more than a technical expedient, which 

 only becomes of importance when it is brought into the 

 service of a scientific idea. In some journals the matter has 

 of late been misrepresented, in that my single cell culture is 

 described as the essential part of the reform to which my 

 yeast studies have given rise in the fermentation industry. 

 This is, however, an error. The essential point is the new 

 principle the selection of a certain species or race. Conse- 

 quently the commonly used terms "pure yeast," "pure 

 cultivation," do not give a correct idea of the subject. 



3. THE CONTRIBUTIONS OF PREVIOUS INVESTIGATORS. 



Just as every investigation is based upon the researches 

 of previous workers, so also was this the case with my 

 researches. In the last section we have become acquainted 

 with the standpoint of our subject at the time when I 

 commenced my studies in connection with the technique of 

 the methods of pure culture ; before proceeding further it 

 will be useful to briefly consider also the previous investi- 

 gations on the yeasts and their relationship to the brewing 

 industry. 



C" The foundations of the science of the micro-organisms of 

 fermentation were laid about sixty years ago, and more 

 especially by the discoveries of Cagniard Latour, Schwann, 

 Turpin and Kutzing. The experiments of Cagniard Latour 



