10 THE AMERICAN MONTHLY [Jan., 



distinguished from those of the true yeasts."^' At c we 

 find some rectangular cells more refractive than those of 

 a yeast, and with vacuoles ; d shows cells of a pastorian 

 form. 



The spore- culture showed. 



1. Spores in the round or oval cells by 25° after 40//. 

 Spores also in the pastorian cells. The first are spores 

 of a cultivated yeast, the latter not. 



2. By 15° C. : After 407i. no spores, after 12h. spores 

 in the pastorian cells, typical wild yeast spares. 



An absolutely pure culture showed that this wild yeast 

 was Sacch. pastorianus III Hansen. 



The spore-culture was overgrown with a mass of rec- 

 tangular cells of a low refractive power (grayish appear- 

 ance). These belong to Mycoderma cerevisicB Desma- 

 ziereSjf and this species is not difiicult to determine. On 

 beer or wine exposed to the atmosphere, a gray, greasy 

 looking zoogloea generally appears after a few days. 

 The zoogloea soon becomes uneven at the surface. The 

 cells are not easily separated, but aggregate in small 

 lumps in the field of the microscope. 



LITERATURE. 



A. Joergensen : The micro-organisms of fermentation. 

 London, 1889. 



Papers by Hansen, Holm and Poulsen in Meddelelser 

 fra Carlsberg Laboratoriet, Vol. I — III (1878—1893) : pa- 

 pers on spore-formation. 



cells, so it does not belong to the true Saccharoinyces. The cells are always 

 readily recognized on account of their typical shape. 



*0n the limitation of these, see Bay (Amer. Naturalist XXVI, p. 694-696, 

 1892). 



t3Iyc. cerev. and M. vim cannot theoretically be separated from each other. 

 Many text books state that these forms have spores ; this was stated by .1. ae 

 Seynes in 1868 and was repeated by others (see DeBary : Comp. Morph. and 

 Biol., 1887. p. 268), though practical work shows that the Mycoderma does 

 not have spores, and that, owing to the uncertainty of the species-question in 

 1868, De Seynes must have been working with true yeasts. 



