2 BULLETIN 819, U. S. DEPARTMENT OE AGRICULTURE. 



The investigation here reported was undertaken to determine the 

 distribution of this " pink yeast," and to find a suitable method of 

 controlling or preventing its development. Later, the work was ex- 

 tended to cover a more detailed study of the organism itself, includ- 

 ing its morphology, physiology, and biochemistry. 



While much concerning the pink yeast and its relation to the oyster 

 industry remains to be studied, the data given in this bulletin may 

 help to a better understanding of the cause of the color, the distribu- 

 tion of the organism, its control, and some of its physical and chemi- 

 cal properties. 



HISTORICAL REVIEW. 



The true yeasts, Saccharomycetes, and the pseudo yeasts, or Tor- 

 ulacese, are widely distributed, and have been isolated from many 

 sources. L. van der Hulle and H. van Laer (1890) isolated a pink 

 yeast from Belgian beer. M. Ward (1892) studied a pink yeast 

 which was an alien organism in ginger beer yeast. Kramer (1891) 

 obtained a pink yeast-like form from must fermentation, while V. 

 Peglion (1895) and E. Kayser (1890) also studied pink yeasts 

 from must fermentation. R. Demme (1890) studied and described 

 a pink form from milk and cheese, and pink yeasts from milk and 

 butter have also been described by Krueger (1892) and R. Rein- 

 mann (1900). B. Fischer and K. Brebeck (1894) describe pink 

 yeasts from the stomach of a patient suffering from gastric fermen- 

 tation, also a pink yeast from samples of sea water south of the 

 Azore Islands. 



The opinion that Torulaceae are merely stages in the develop- 

 ment of other fungi has been expressed by many workers, notably 

 by Hansen (1898). E. Klein and N. Gordan (1912) claim that a cer- 

 tain pink yeast originates in a rust infecting the Canada thistle, Puc- 

 cinia suaveolens. On the other hand. R. Meissner (1899) has shown 

 differences between the budding Torula forms and the budding cells 

 of the fungus causing peach leaf curl, Exoascus deformans. It is 

 claimed by Laurent (1889) that the budding spores of Cladosporium 

 herbarium become pink yeasts. The earliest attempt to study 

 these pink or red yeasts was made by F. A. Janssens and A. Mer- 

 tens (1903) with an organism described as a " red Torula." Such 

 forms, which have been known for a long time, were first described 

 by Fresenius (1850) as Cryptococcu-s glutinis. Later Schroter and 

 Cohn (1872) grouped the pink yeast with the Saccharomycetes, but 

 Hansen has shown that Cryptococcus glutinis comprises several 

 species and can not be included in the Saccharomycetes. Hansen 

 (1902) and P. Lindner (1887) were unable to see any sporulation in 

 the red budding fungi, and Elfving (1886) also studied a pink yeast 

 which did not form spores. A. P. Swan (1896) described a red 



