296 O. W. HUNTER 



rary stage of development of yeasts. He has demonstrated that, 

 at the least, spore production is not a stable factor, for he has 

 been able to produce an asporogenic race of Saccharomyces by 

 varying the condition of cultivation. This would lead one to 

 doubt the usefulness of attempting to use sporulation in yeasts as 

 of much diagnostic value. 



MORPHOLOGICAL, CULTURAL AND BIOCHEMICAL CHARACTERISTICS 



The yeast causing "foamy cream" is oval to elliptical in shape, 

 averaging 5 microns in length and 2 microns in breadth. 



Typical spores were not demonstrated by cultivation upon 

 gypsum blocks or potato at temperatures of 25°C. and 35°C. 

 According to the present means of classifying yeasts, the organ- 

 ism is therefore a false yeast or torula. The average colony 

 varies from 2 to 3 mm. in diameter; but more minute forms are 

 frequently noted. In appearance the colonies are spherical with 

 smooth edges, having a raised smooth glistening surface. Plate 

 cultures of the organism emit a yeasty or fruity odor. Upon 

 lactose agar it grows moderately, exhibiting a raised, smooth, 

 and dull to glistening growth. It produces a slight cloudiness 

 in sugar broth; no pellicle, acid reaction in litmus milk; and fails 

 to Hquefy gelatin. In milk about 0.3 per cent acid is produced. 

 Gas production was demonstrated in glucose, lactose, sucrose, 

 levulose, galactose, maltose and bile lactose; although the action 

 in galactose, maltose and bile lactose was slow and feeble. 



The relation of temperature to the rate of fermentation of the 

 organism is represented in table 1. Litmus milk fermentation 

 tubes were inoculated with 0.1 cc. broth culture of the yeast and 

 incubated at 18°C., 25°C. and 37°C., respectively. The results 

 are self explanatory and easily account for the predominance of 

 foamy cream during hot weather. The highest temperature 

 studied, 37°C., is not necessarily the optimum temperature for 

 the development of the organism, but lack of inciabation facilities 

 prevented a more exact study of this point— 



