366 MICRO-ORGANISMS AND FERMENTATION. 



a fish broth containing 10 per cent, of sodium chloride. In a 

 nutritive liquor which contains less than 3 per cent, of salt 

 the growth ceases. The cells do not alter their round shape 

 in nutritive liquids with varying quantities of salt. It produces 

 no fermentation in apple juice. 



Saccharomyces Hansenii Zopf 



was discovered amongst the fungi of cotton-seed meal. It 

 forms spherical spores of very minute diameter, which are 

 developed singly or never with more than two in a mother 

 cell. In fermentable saccharine solutions it produces no 

 alcoholic fermentation, but crystals of calcium oxalate are 

 observed in the sediment. Zopf found a similar formation in 

 nutritive solutions containing galactose, grape-sugar, saccha- 

 rose, lactose, maltose, dulcite, glycerine, and mannite. 



Saccharomyces minor Engel. 

 The vegetative cells are completely spherical, measuring 



6 fj. in diameter, and are linked in chains or specks con- 

 taining six to nine cells. The spore-forming cells measure 

 7 to 8 ju, and contain from two to four spores of 3 /u diameter. 



Engel believes this organism to be the most active ferment 

 in the fermentation of bread. The author has frequently 

 found this minute spore-forming yeast in the sour dough of 

 the Copenhagen bakeries. 



Pichia membranaefaeiens or Saccharomyces membranae- 

 faciens Hansen. 



This peculiar species, which occupies a special place amongst 

 the Saccharomycetes, yields a strongly-developed light grey 

 wrinkled film when grown in wort, which rapidly covers the 

 Avhole surface of the liquid, and consists mainly of sausage- 

 shaped and elongated oval cells ; these have strongly-developed 

 vacuoles, and a more or less empty appearance. Separating 

 the colonies is an abundant admixture of air. 



The limits of temperature for budding on wort are 35 to 

 36 C., and 0-5 C. When this species is cultivated near the 

 limiting temperature, it occurs entirely as sedimentary yeast. 



