ALCOHOLIC FERMENTS. 129 



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 very imperfect methods of experi- 

 menting of that time permitted a conclusion being drawn, 

 it appeared probable that there was a separate group of such 

 budding-fungi, and to this group EEESS gave the name 

 Saccharomyces}- 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 forma- 

 tion 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; 

 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 Saccharomy- 

 cetes, spore-forming cells were obtained or not it is easy to 

 understand the doubt subsequently expressed as to the exist- 

 ence of spores, and the disputes which followed as to whether 

 the yeast used in practice had or had not lost the property of 

 forming spores. Finally, BREFELD believed he had definitely 

 proved that cultivated yeast was completely deficient in this 

 property. This confusion was at last dissipated and order 

 established when HANSEN discovered the conditions regulating 

 the formation of spores, and upon this basis for the first time 

 devised a method for obtaining them. 



PASTEUR'S " fitudes sur la Mere " was published in the year 



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 BAKY in "Comparative Morphology and Biology of the Fungi, Myce- 

 tozoa and Bacteria," Oxford, 1887. REESS thus, at once, destroyed the very 

 system, the construction of which he had just undertaken. 



I 



