48 STRONG DRINK AND TOBACCO SMOKE. 



a microscopic infusorium ; although so far back as 

 1680 the great Leeiiwenlioek had both figured and 

 described it as a plant. 



If a small portion of fresh yeast is placed on a slip 

 of glass under the microscope, and fed with a moderately 

 strong solution of sugar or saccharine matter, such as 

 fresh worts, it will exhibit a singular appearance. 

 It is composed of a series of cells with minute dots 

 or nuclei contained within them, and they are so 

 transparent that the cells can be seen through over- 

 lying one another. After being in the brewer's worts 

 an hour or so, these cells begin to germinate by a pro- 

 cess of buddino;. In the course of about three hours 

 the younger cells have attained to the dimensions of 

 then- parents, and in about eight hours they begin to 

 form into filaments. At the end of three days they 

 become branched. 



Turpin states that in the brewing of 14 butts of beer, 

 in which 35 pounds of dried yeast had been used, 212 

 pounds of new yeast were produced ; in other words, 

 the plants had multiplied to 605 times their original 

 quantity, an astonishing iiicrease for the short jperiod 

 occupied in their production. 



There is, however, a difference in the appearance 

 between what is known as top yeast and bottom yeast, 

 when viewed under the microscope. The former consists 

 of large cells, at the extremities of which small ones 

 are developed ; it would, therefore, appear to be pro- 

 duced by a process of Inidding of individual cells. A 



