126 PHYSIOLOGY OF YEASTS (Continued) 



able to ferment lactose. Beijerinck has also confirmed this. This 

 author found S. Kephir. 



Sartory l has recently described a yeast which sporulated only 

 in the presence of a bacterium with which it lives. 



Rist and Khoury, 2 on the other hand, have observed a similar 

 phenomenon in the fermentation of leben, an Egyptian fermented 

 milk. This fermentation is due to two yeasts, the S. lebenis and 

 Mycoderma lebenis, and a bacterium Streptococcus lebenis. The two 

 yeasts alone are not able to ferment the lactose. But, associated with 

 Streptococcus lebenis, they bring about the fermentation of the milk. 

 The bacterium seems, then, to act on the lactose in some way to make 

 it available for .the yeasts. 



Another very curious example of symbiosis is furnished by the 

 parasites in that rare infection in man known as " black tongue." 

 Guegen's 3 work seems to indicate that this disease is caused by a 

 mold Oospora lingualis and a yeast Cryptococcus linguae-pilosae. The 

 yeast functions only when it is in association with the mold. These 

 observations have been confirmed by the investigations of Thaon. 4 



Carpano 5 has reported that, in infections by Cryptococcus farcimi- 

 nosus, Staph. pyogenes aureus and Strept. adenitis equi are found. Pos- 

 sibly this is another symbiotic relationship. 



It may be possible to have symbiotic relations between certain 

 yeasts and the cholera vibrio, for Metschnikoff has shown that this 

 latter organism is favored by the presence of a Torula. 



One is able to cite many examples in which two forms of life are 

 able to live together. However, up to the present time, we have only 

 observed symbioses between two yeasts or between a yeast and a bac- 

 terium. It is possible to have symbiosis between two totally dif- 

 ferent organisms, such as a yeast and an animal. Thus, Lindner 6 

 found Saccharomyces apiculatus parasiticus in an hemoptera, Aspidi- 

 otus Neriij in which it was always present without seeming to exer- 



1 Sartory, A. Speculation d'une levure sous 1'influence d'une bacterie. Comp. 

 Rend, des Soc. Biol. 72, 1912. 



2 Rist, E. and Khoury, J. Etude sur un lait fermente comestible. Cent. 

 Bakt. and Leben d'Egypte. Ann. Past. Inst. 1902, 16. 



3 Guegen, F. Sur Oospora lingualis et Cryptococcus lingualis. Arch, de 

 Parasit. 1909, 12. 



4 Thaon, P. Symbiose de levure et Oospora dans un cas de langue noire. 

 Soc. de Biologic, 67. 1909. 



6 Carpano, M. The association of bacteria in Cryptococcus farciminosus in- 

 fection. Ann. Ig (Rome) 28, 273-279. 1918. 



6 Lindner, P. Das Vorkommen der parasitischen Apiculatus Hefe in auf 

 Hefen schmarotzenden Schildlausen und deren mutmassliche Bedeutung der 

 Nonneraupe. Wochen. f. Brauerei, No. 3, 1907, 



