ii8 MORPHOLOGY AND LIFE-HISTORY OF YEASTS. 



berg Bottom- Yeast No. i, the first yeast prepared by the pure- 

 culture method, and by means of which E. Chr. Hansen 

 introduced his pure-culture method into practice, at the Altr 

 Carlsberg brewery, in 1883. It was isolated as the principal 

 constituent of the same stock yeast, which was found to be in- 

 fected with the aforesaid Saccli. Pa4orianus T. A characteristic 

 feature of this yeast is the preponderance of pointed oval cells, 

 those of purely globular form being very much in the minority. 

 Elongated cells also are very rare. On the other hand, the 

 Carlsberg Bottom-Yeast No. 2, shown in Fig. 131, is character- 

 ised by the more rounded appearance of its cells, and by the 

 occuiTence of unusually large, or giant, cells, one of which can 

 be seen on the left of the illustration. The appearance of these 



Fig. 130.— Carlsberg Bottom- Yeast No. i. 



Cells from the sedimental yeast at the close 

 of primary fermentation. Magn. 1000. (After 

 Hansen.) 



Fig. 131.— Carlsberg Bottom-Yeast No.''2. 



Cells from the sedimental yeast at the close 

 of primary fermentation. Magn. 1000. (After 

 Hansen.} 



giant cells is specially remarkable in some species, and then 

 forms a good indication. Thus, Beyerinck (XX.) found large 

 cells attaining as much as 20 /x in diameter, in old agar-agar 

 cultures of a budding fungus known as Sarrh. Kefi/r, which he 

 had isolated from the Kephir to be described in our final 

 chapter, whereas the other cells measured only 5 to 6 /x. 



The sedimental yeast found deposited at the bottom of the 

 fermenting vessels at the close of primary fermentation, in 

 bottom-fermentation breweries, is drawn off — after the removal 

 of the young beer — through an orifice in the bottom of the tun, 

 and is collected in a vessel wherein it is washed with water, to 

 be afterwards stored under ice water until required for pitching 

 a subsequent brew. This yeast, it may be stated, is a highly 

 diversified mixture. Apart from the pos.sible presence of 

 several species of yeast and bacteria (.vrarma, c^'c), it also 

 contains sundry other ingredients, the mo.st importiint of 

 which are : First, salts of lime, chiefly the oxalate, immediately 

 recognisable under the microscope by its octahedral, rhombo- 

 hedral or flat tabular crystals. These have been precipitated 

 during fermentation. Their origin is only to a small extent 



