87 



number of species of Agardh's supposed genus Hyyrocrocis, 

 as H. acida, vini, rosce, atramenti, salvice, &c. 



In the fermenting fluids occur however several other things 

 of difficult determination ; thus I noticed in the beer-yeast 

 excessively delicate confervoid forms, which are generally 

 somewhat longer than the single articulations of the Saccha- 

 romyces, but are at the most only one-tenth in breadth ; they 

 are not of like length, and increase by division into still smaller 

 threads. They are only sufficiently evident with a magnifying 

 power of 300. In the expressed juice of the grape I observed, 

 besides the two above-described plants, a delicate white sedi- 

 ment, which adhered to the glass at the margin of the fluid ; 

 it was formed of innumerable perfectly round and equally 

 sized bodies, which were about one-tenth the size of the arti- 

 culations of the SaccharomyceSy and in the course of from 

 three to four days disappeared entirely. 



The number of vegetable forms which occur in the ferment- 

 ing juices of fruits is consequently very great, and whether 

 the phenomena of fermentation depend on the one or the 

 other cannot be decided. M. Schwann instituted some obser- 

 vations with the vinous fermentation, whence he concluded 

 that in vinous fermentation as also in decomposition it is not 

 the oxygen of the atmospheric air which produces it, but that 

 it is a substance destructible by heat contained in the atmo- 

 sphere. A solution of sugar was mixed with yeast, exposed 

 .for ten minutes to the temperature of boiling water, then 

 brought into a small bottle under mercury, and some heated 

 air (one-fourth to one-third of the volume of fluid) conducted 

 into it. The bottles with the heated air were then closed with 

 a stopper and placed aside in a temperature of 10 to 14; they 

 evinced however no phenomena of fermentation, while other 

 bottles with the boiled fluid, into which however no heated 

 air had been conducted, were in the course of four to six weeks 

 broken into pieces from the development of the gas. The 

 phenomena widen M. Schwann observed in these experiments 

 are in effect very remarkable, but they might probably be ex- 

 plained in some other way : the temperature of boiling w r ater, 

 it is true, does not destroy the Saccharomyces as previously 

 stated ; but we also know that even the germination of the 

 seeds of higher plants does not take place in perfectly boiled 

 water, although exposed to the atmosphere. 



