APPENDIX I. 



YEASTS AND MOULDS. 



Yeast-fungi and mould-fungi, like bacteria or fission-fungi, are- 

 achlorophyllous Thallophytes. They belong to two separate orders 

 the Saccharomycetes and Hyphomycetes which are intimately related 

 to each other, but quite distinct from bacteria. Their germs occur 

 widely distributed in air, soil and water, and are constantly 

 encountered in bacteriological investigations. In addition, many 

 species are of hygienic and pathological interest and importance in 

 being either accidentally associated with, or the cause of various 

 morbid processes and fermentations. For a complete account of 

 all the described species and full details of the various forms of 

 development, reference must be made to botanical and other 

 works.* A description of certain species is appended here, and may 

 afford some useful information to the worker in a bacteriological 

 laboratory. 



YEAST- FUNGI OR SACCHAROMYCETES. 



Saccharomyces cerevisise (Torula cerevisice). Cells round or 

 oval, 8 to 9 //, long, singly or united in small chains. Spores 

 occur three or four together in a mother-cell, 4 to 5 /A in diam. 

 S. cerevisise, S. pastorianus and S. ellipsoideus are active alcoholic 

 ferments. According to Jorgensen they will produce in fourteen 

 days in beer-wort from 4 to 6 per cent., by volume, of alcohol. 



Saccharomyces ellipsoideus (Hansen). I. Elliptical cells, 

 mostly 6 /A long, singly or united in little branching chains. Two to 

 four spores found in a mother-cell, 3 to 3*5 //, in diam. Cultivated 

 on the surface of wort-gelatine they produce in eleven to fourteen 

 days, at 25 C., a net-like growth by which they can be recognised 



* Sachs, Text-book of Botany ; Jorgensen, Micro-organisms and Fermen- 

 tation. 



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