APPENDIX I. 



YEASTS AND MOULDS. 



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

 acMorophyllous Thallophytes. They belong to two separate orders — 

 the Saccharmnycetes 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 constantlj^ 

 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 

 ^11 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. 



Ybast-pungi or Sacchaeomtcetes. 



SaccharomyGes cerevisiae (Torula cerevisice). — Cells round or 

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

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



Saeeharorttyees ellipsoideus (Hansen). I. — Elliptical cells, 

 mostly 6 [i long, singly or united in little branching chains. Two to 

 four spores found in a mother-cell, 3 to 3'5 fi, 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. 



577 37 



