SACCHAROMYCES WILLIANUS 



245 



The ascospores are usually 5 fj, in diameter (Fig. 116). Accord- 

 ing to Marchaud, they germinate after having copulated. 



Temperatures for Formation of Scum 

 At 40 no formation of scum. 



36-38 at the end of 8-12 hours feeble formation. 



33-34 " 



26-28 " 



20-22 " 



13-15 " 



6-7 " 



3-5 " 



" 3-4 



" 4-5 " 



" 4-6 



" 8-10 " 



" 1-2 months 



" 5-6 



2-3 no formation of scum. 



The microscopic appearance of the 

 cells in the scum varies. At the beginning 

 the cells look like those in the sediment 

 but, as a rule, they are a little longer. 

 In old scums, one may see colonies with 

 short and long cells or tubular cells with 

 branching projections. We have seen that 

 Hansen was able to transform this yeast, 

 normally a bottom yeast, into a top yeast. 



Fig. 116. Ascs in Saccharo- 

 myces turbidans (after Han- 

 sen). 



SACCHAROMYCES WILLIANUS. Saccardo 1 

 Syn: SACCHAROMYCES i OF WILL. Bay 2 



The species has been described and named by Will, 3 with the 

 provisional name of yeast No. 811. It is a bottom yeast related 

 to S. turbidans. Its cells are egg-shaped. 



The limits of temperature for the formation of ascospores on 

 plaster blocks are 39-41 C. and 4-9 C. The optimum is 34 C. 

 At this temperature sporulation appears at the end of 11 hours. The 

 ascospores measure 1.5 to 5 /A in diameter, more often 3-5 JJL. They 

 appear at first very refractive, homogeneous, and show vacuoles with 

 fat globules. Their number never exceeds four for each asc. They 

 germinate ordinarily after having copulated. The temperature limits for 

 the formation on beer wort of a scum are 39-41 C. and 45 C. The 

 cells of the scum are elongated and form branching colonies. The 



1 Saccardo, P. A. Syllage fungorum. Padoue, II, 1895. 



2 Bay, J. C. The sporeforming species of the genus Saccharomyces. The 

 American Naturalist, XXVII, 1893. 



3 Will, H. Zwei Hefearten welche abnorme Veranderungen in Bier veran- 

 lassen. Zeitschr. f. d. ges. Brauw., XIV, 1891. 



COLLEttt 



ot PHARMACH- 



