238 FAMILY OF SACCHAROMYCETACEAE 



The ascs are elongated (Fig. 105) and possess a number of asco- 

 spores which vary from 1 to 4 and may attain the number of 5 or 10. 

 The size of the ascospore is quite variable; it varies between 

 1.5 and 3.5 microns and goes rarely to 5.0 microns. The ascospores 

 never undergo copulation, which distinguishes S. pastorianus from 

 S. intermedius and S. validity (Marchaud). 



Temperatures of Scum Formation 

 At 34 no scum formation. 



26-28 at the end of from 7 to 10 days, feebly developed. 

 20-22 " " " " " 8 to 15 

 13-15 " " " " " 15 to 30 " 

 6-7 " " " " " 1 to 2 months " 

 3-5 " " " " " 5 to 6 " " " 



2-3 no formation of a scum. 



The microscopic appearance of the cells in the scum is as follows: 

 At 20-28 C. the cells present the same shape as in the deposit. At 

 13 to 15 C., vigorous colonies are seen having the appearance of a 

 mycelium composed of ordinary cells elongated and in the form of 

 chains (Fig. 106). In old cultures of scums, the cells are smaller 

 than in the sediment. One finds queer cells sometimes almost filiform. 

 This yeast ferments saccharose, dextrose, levulose and maltose. 



SACCHAROMYCES INTERMEDIUS. Hansen l 

 Syn. SACCHAROMYCES PASTORIANUS II. Hansen. Also Rees 



This yeast produces a feeble top fermentation. It was discovered 

 by Hansen in the air of breweries in Copenhagen. 



ft does not seem to 

 cause any disease in 



the beer * Hansen 

 has provisionally 



named it Saccharo- 



myces pastorianus II. Fig. 107-A. Germination of As- 



t f rms 



from Sediment in sediment of elon- i, without Copulation;" 2-9, Af ter Copu- 



, , 



gated cells in chain 



formation. (Fig. 107.) One finds also large and small round or oval 

 cells. The temperatures of budding on beer wort are: minimum, 

 0.5 C.; maximum 40 C. 



1 Hansen, E. C. See references for Saccharomyces pastorianus. 



