1870.] Beer, Scientifically and Socially Considered. 305 



Yeast is a lowly unicellar plant called Torula cerevisim. The 

 growth of its cells (which on examination with the microscope are 

 found to contain minute nuclei) has been ably described * by an 

 eminent botanist (Dr. Henfry), who obtained some fresh wort in 

 which fermentation had commenced and placed a drop of the liquid 

 under the microscope. At first, he says, these globules enlarged 

 until they attained a certain size, and then they remained unchanged 

 for a time. Next, a little point-like bud was seen to project from 

 one portion of the cell- wall, and this grew until it attained the same 

 size as the parent cell. This occupied about three hours, and by a 

 repetition of the process sixteen cells were developed from a single 

 one. After a time the growth slackened and at length it ceased, the 

 observer believed, " undoubtedly because all was removed from the 

 liquid which could serve for 



their growth." The following FlG - 7 - FlG - 8 - 



woodcuts represent the micro- 

 scopical appearance of the cells 

 of the yeast fungus, Fig. 7 being 

 that found at the bottom, and 

 Fig. 8 a "white mealy sub- 

 stance," at the top of the liquid ; 

 the growing globules will be seen in the former, from which my 

 microscopical readers will perceive that the plant multiplies by the 

 well-known but incomplete process of fission. 



These, then, are the materials which should be employed in the 

 brewing of good ale. Water, free from organic matter and con- 

 taining sulphate and carbonate of lime ; barley, in the form of malt ; 

 hops, and yeast ; and although the reader will have gathered from 

 the preceding short account of these substances, what leading prin- 

 ciples are involved in their use and treatment, I propose briefly to 

 recapitulate the changes which occur in the brewing process, before 

 attempting to describe the practical operation. In the malting or 

 germination of the barley the albumen in the grain becomes con- 

 verted into diastase, the property of which is to change the starch 

 (also constituent in the barley) into soluble dextrin or gum, and 

 sugar, and consequently the malt possesses a sweet taste which is 

 not present in the grain previous to malting. In the mashing 

 process, this sweet substance is washed out of the malt, and with 

 the water employed for the purpose goes to form the "wort" or 

 stock of the beer. This " wort " is subsequently boiled with hojos, 

 which contain a bitter principle, lujoulite, and an essential oil, of 

 which the effect is to impart a bitter aromatic flavour to the beer, 

 at the same time as the chief organic constituents of the wort are 

 removed. And finally through the introduction of yeast, a minute 



* ' Micrographic Dictionary ' (article " Yeast- Plant "), from which, with the 

 publisher's permission, the woodcuts are copied. 



