SACCHAROMYCES 277 



2. Fermenting glucose, sucrose, and one third of the raffinose. 



a. Cells elongated. S. muciparis 



b. Cells round or oval. 5. Chevalieri 



and varieties: Lindneri and torulosus 



3. Fermenting glucose, sucrose, raffinose, and melibiose. S. microellipsoideus 



4. Fermenting glucose, galactose, sucrose, and one third of the raffinose. 



a. Cells small, round, or sUghtly oval. -S'. exiguus 



b. Cells larger, oval. S. Mangini 



and variety: tetrospoms 



5. Fermenting glucose, sucrose, and maltose. S. heterogenicus 



6. Fermenting glucose, sucrose, maltose, and one third of the raffinose. 



a. Cells egg-shaped. S. oviformis 



b. Cells elongated. - S. Bayanus 



7. Fermenting glucose, galactose, sucrose (weakly), and maltose. 



S. Chodati 



8. Fermenting glucose, galactose, sucrose, maltose, and one third of the raflEinose> 

 a. Cells in young wort cultures round, oval, egg-shaped, or pear-shaped. ^^^ 



S. cerevisiae '^ 

 and varieties: ellipsoideus, turbidans, 

 Marchalianus, pulmonalis, fesiinans 

 h. Cells in young wort cultures oval to sausage-shaped. S. intermedius 



c. Cells in young wort cultures long oval, very large. S. Villianus 



d. Cells in young wort cultures oval, but elongated, sausage-shaped, on agar. 



S. Odessa 



e. Cells much elongated (up to 30m) on agar. S. tubiformis 



f. Cells in young wort cultures round to oval, on agar becoming irregular cell- 

 complexes. S. paradoxus 



9. Fermenting glucose, galactose, sucrose, maltose, raffinose, and meUbiose. 



a. Cells in young wort cultures elongated, sausage-shaped, forming long strands 

 of pseudomycelium. *?• Pastorianus 



b. Cells in young wort cultures single or in twos and threes. 



I. Cells oval. S. carlsbergensis 



and varieties: monacensis, valdensis, 

 mandshuricusii, polymorphus 

 II. Cells much elongated. -S. validus 



III. Cells long oval. S. Logos 



IV. Cells oval on wort, filamentous on agar. S. uvarum 



10. Fermenting glucose, galactose, sucrose, lactose, and one third of the raffinose. 



S. fragilis 



It will be noted by the key that the familiar Saccharomyces 

 ellipsoideus, the wine yeast, has been reduced to a variety. Elon- 

 gated yeasts ordinarily diagnosed as S. ellipsoideus isolated from 

 fermenting fruit juices tend to lose on cultivation their characteristic 

 elongated oval shape and tend to become indistinguishable from the 

 round S. cerevisiae, a common ale and bakery yeast. The differences 

 between the species and the variety are not such as make a clear 

 delineation. The differences are tendency of S. cerevisiae var. ellip- 

 soideus to elliptical shape when first isolated and S. cerevisiae to 



