8o RESEARCHES ON YEASTS. 



be observed with regard to the budding-systems which 

 precede the development of the spores.* 



It is self-evident that species cannot, in all cases, be 

 distinguished from one another by means of one of the 

 characters mentioned, but that several characters must fre- 

 quently be made use of for this purpose. The characters 

 afforded by the development of the spores are of especial 

 importance ; I have made use of these as the foundation of 

 my method for the analysis of low-fermentation brewery 

 yeast, and the more so because they enable us without 

 first preparing a pure culture to make a direct analysis 

 when it is a question of determining whether disease yeasts 

 are present or notf This analytical method is rendered 

 still more sensitive by the employment of tartaric acid, as 

 described on p. 151. 



A series of Saccharomycetes has thus been found which 

 are differently affected by external influences. That the 

 observed characters are not quite of the same kind as those 

 with which we are acquainted in the case of the higher 

 organisms, is not to He wondered at when we bear in mind 



* The above investigations were published in ' Compte-rendu des travaux du 

 laboratoire de Carlsberg,' Copenhagen, 1882, 1883, 1886, 1888 and 1891. A 

 German translation of the French resumes was given by the editor of the 

 * Zeitschr. f. d. ges. Brauwesen,' and appeared in that journal for the corre- 

 sponding years. The behaviour of yeast cells on solid media, and the above- 

 mentioned difference in the structure of spores were discussed in my lecture 

 delivered at Gratz on June 12, 1887 (see 'Zeitschr. f. Bierbrauerei, ' Vienna, 

 1887, p. 518, and 'Centralbl. f. Bacteriologie und Parasitenkunde,' 1887, ii. 

 p. 118). 



The terms "culture yeast," "culture species," "brewery yeast," &c., do 

 not imply that these species have been produced by cultivation for as yet 

 nothing is known with regard to this but merely that they are employed in 

 the industry. All other Saccharomycetes are, on the contrary, spoken of as "wild 

 yeasts," "wild species." So far as experiments indicate, we may assume that 

 not only the so-called wild yeasts, but also the culture yeasts occur in nature. 



t See Just. Chr. Holm et S. V. Poulsen:' "Jusqu'a quelle limite peut-on, 

 par la methode de M. Hansen, constater une infection de 'levure sauvage' 

 dans- une masse de levure basse de Saccharomyces cerevisise?" Compte-rendu 

 des travaux du laboratoire de Carlsberg, Copenhague, vol. ii. livr. iv. 1886, 

 et livr. v. 1888. A German translation appeared in the 'Zeitschr. f. d. ges. 

 Brauwesen ' for the corresponding years. 



