390 MOULDS AND YEASTS 



A piece of stout cardboard, cut in a similar manner, may be 

 used instead of blotting-paper. 



In the centre of a cover-slip place a small drop of water, or a 

 drop of a very dilute extract of French plums which has been 

 boiled. Shake or otherwise transfer the spore to be germinated 

 into the drop of water, and then place the cover-slip over the 

 hole in the cardboard with the drop hanging downwards, as in B, 

 Fig. 56- 



Keep the whole on damp blotting-paper under a bell-jar. 



The spores can be readily examined from day to day, even 

 with a high power, through the glass of the cover-slip without 

 moving or disturbing the latter. 



Yeasts {Saccharomyces and Torula). 



I . Saccharomyces. The term yeast is applied to a large 

 series of simple unicellular fungi which have the power 

 of producing alcohol when grown in the juices of fruits, 

 malt-extract or " wort," and other solutions containing 

 sugars. 



Those which are included in the genus Saccharomyces 

 reproduce themselves in two ways, viz : 



(a) By the process of sprouting, budding, or gemma- 

 tion. 



(b) By means of specialized spores (ascospores). 

 Certain unicellular fungi, closely resembling yeasts 



in form and size, and in the sprouting process, but which 

 do not form ascospores, are classified as belonging to 

 the form -genus Torula. 



In the vegetative state yeast plants consist of single 

 oval cells, which under certain conditions may become 

 considerably elongated so as to resemble hyphal fila- 

 ments, but no true mycelium is formed by these fungi. 



The yeast-cell has an elastic cell-wall filled with 

 protoplasm in which are one or two large vacuoles. 



