MICROBES, MOULDS, AND YEAST. 



215 



usually employed in breweries in being exceedingly 

 impure and containing a mixture of many different 

 kinds. 



Fig. 27. — ^Yeast Spores and Aitaratus for Cultivation. The spores 

 figured are those of (i) Schizosaccharomyces sp. (a species from Jorgensen's 

 laboratory found in Greek wine) ; (2 and 3) Saccharomjxes ellipsoideus var. II. ; 

 (4) S. cerevisiae var. ; (5) S. anomalus. ; (6) S. Pastorianus var. I. ; (7) S. mahwra. 

 Below are seen a Freudenreich flask for yeast cultures and a glass shell with 

 plaster of paris block and its lid with a label. 



Although the plants mentioned in this chapter are 

 all exceedingly minute, it is clear that they are of very 

 great practical importance. The work of Pasteur, 

 of Lister, of Hansen, and of Koch, is all very recent ; 

 and yet it has revolutionised modern medical practice 

 in many directions. All sorts of interesting possibilities 

 can be imagined when a similar high level of achieve- 

 ment has been reached in other directions. We can 

 see that the farmer will regularly sow his bacteria and 



