112 MICRO-ORGANISMS AND FERMENTATION. 



however, the first who distinctly described the spores in yeast- 

 cells. Shortly afterwards, in the year 1870, Reess proved 

 that the formation of spores occurred in several species of 

 yeast, and stated that the germination of these endogenous 

 cells took place by budding. As far as the, at that time, very 

 imperfect methods of experimenting permitted a conclusion 

 being drawn, it appeared probable that there was a separate 

 group of such budding-fungi, and to this group Reess gave 

 the name Saccharomyces. 1 The conditions favourable to the 

 formation of such reproductive organs in the cells were, 

 however, unknown ; there was no definite method by means 

 of which their formation could be insured, and experiments 

 having this for their object were made at random. In the 

 work already quoted Reess also proposed a system for the 

 classification of the Saccharomycetes, which he based solely 

 upon the size and form of the cells. Such a classification 

 founded upon purely microscopical appearances, has, however, 

 proved to be useless, and it is impossible to distinguish 

 between the different species by means of the characters 

 indicated by Reess. His work has consequently been of no 

 real practical importance ; and since the essential conditions 

 for the formation of spores were unknown to him and to his 

 successor Engel so that it was purely a matter of chance 

 whether, in a culture of Saccharomycetes, spore-forming cells 

 were obtained or not it is easy to understand the doubt 

 subsequently expressed as to the existence of spores, and the 

 disputes which also followed as to whether the yeast used in 

 practice had or had not lost the property of forming spores. 

 Finally, Brefeld believed that he had definitely proved that 

 cultivated yeast was completely deficient in this property. 

 This confusion was at last dissipated and order established 



1 The same author was however less consistent when he admitted 

 into this group other kinds which did not yield spores, and in this he 

 was also followed by de Bary in ''Comparative Morphology and 

 Biology of the Fungi. Mycetozoa and Bacteria," Oxford, 1887. Reess 

 himself thus at once destroyed the very system, the construction of 

 which he had just taken in hand. 



