SCIENTIFIC RESEARCH IN PRACTICE. 



257 



apparatus described below. The main result achieved is that 

 we no longer proceed in a haphazard way, and are not 

 compelled to leave the fermentations to take their chance, as was 

 formerly the case. 



FIG. 80. Yeast- propagating apparatus devised by HANSEN and KUEHLE ; A, air- 

 pump ; B, air-vessel ; C, fermenting-cy Under ; a, window ; 6, 6, 6, stirrer ; c, c, doubly- 

 bent tube ; d, vessel containing water ; I, cock for drawing off the beer and yeast ; 

 /,/, glass tube connected at e and h with the cylinder, and graduated for the measure- 

 ment of fixed quantities of liquid ; g, filter ; i, india-rubber tube placed at the middle 

 of the glass tube ; j, tube with rubber connection for introducing the pure culture ; 

 k, k, connection with the wort-cylinder D ; m, filter ; n, n, doubly-bent tube ; o, vessel 

 containing water ; p, p, cold water tube ; u, tube with cock (s) for introducing wort ; 

 t, outlet-tube for the water used in cooling ; q, cock (the wort is allowed to rise to 

 this height) ; r, cock for drawing off wort. 



Since the various species of yeast differ in their power of 

 resisting competing disease-germs, it is in many cases of great 

 importance to be able, at short intervals, to introduce into the 

 brewery a considerable quantity of a suitable and absolutely 

 pure species of yeast, which has been previously selected by 

 systematic experiments. This object is attained by means of 



