SACCHAROMYCES ELLIPSOIDEUS 245 



on potatoes prepared according to Globig's method. (See Technique, 

 78.) 



The author has found the following simple arrangement yield most 

 satisfactory results. An oblique plaster-of- Paris block is prepared so that 

 it will rest in the bottom of an ordinary test-tube, about 1 in. in diameter, 

 containing a little water in the bottom, which is plugged and sterilized. 

 Some yeast is placed on the upper portion of the oblique surface of the 

 plaster block, when the tube can be placed in the incubator or left at 

 room temperature. 



Staining Reactions. Dried specimens can be stained with fuchsin 

 and methylene blue. This stain is also used to differentiate living and 

 dead cells in hanging-drop cultures, the. latter alone staining. The 

 author has found that ascospores can be beautifully demonstrated by the 

 Cladius method of staining, 12, the cells being stained blue, and the 

 spores and background remaining yellow with the picric acid (see Photo- 

 micrograph, Fig. 96). The ascospores can also be stained by the ordinary 

 method for staining spores (see 26). 



Film Formation. This takes place most rapidly (seven to ten days) 

 at a temperature of from 20 to 22 C., most slowly (two to three months) 

 at 6 to 7 C., and ceases altogether above 38 C. and below 5 C. 



Biological Characters. On Gelatine Plates it forms small white 

 colonies ; under a low power the individual yeast cells forming the surface 

 colonies can be observed. 



It secretes a peculiar substance which, acting on saccharose or crude 

 cane sugar, inverts it to invert sugar. This latter substance is fermented, 

 a similar change taking place in dextrose and maltose, alcohol and car- 

 bonic acid gas being formed, accompanied with an evolution of heat and 

 great multiplication of the yeast cells. On lactose or milk sugar it does 

 not seem to cause any change. 



SACCHAROMYCES ELLIPSOIDEUS. 

 (Divided by Hansen into I. and II.) 



SACCHAROMYCES ELLIPSOIDEUS I. 



This is a ' wild ' species of wine ferment. It is found on the sur- 

 face of fruit, chiefly on wine grapes. 



Microscopical Appearances. Round or oval cells, which sometimes 

 assume a sausage form. 



Spore Formation. The spores are from 2 to 4 ^ in diameter, two 

 to four being found in a single ascus. They are developed between 7J 



