52 THE PLANTS OF FERMENTATION. 



German physician and naturalist, in 1870, and he first attached to 

 them, the following specific names : 



Saccharomyces apiculatis ; which is the first to grow, and the 

 most minute in size. 



Saccharomyces Pastorianus ; which is by far the most active 

 and abundant, and which Dr. Rees named after M. Pasteur : and 

 lastly, 



Saccharomyces ellipsoides ; which is the slowest in growth, but 

 most persistent, and which forms the ordinary ferment of wine. 



M. Pasteur describes minutely from his observations, the life 

 history of these Saccharomyces, their several modes of rapid develop- 

 ment and reproduction, together with the chemical changes they 

 effect by the decomposition of Glucose, such as the production of 

 Alcohol, Glycerine, &c. These plants frequently take different 

 forms, according to the varying circumstances under which they 

 grow ; for example, one form of Saccharomyces Pastorianus is so 

 small that it was at first thought to be a different plant, and it was 

 called by Dr. Rees Saccharomyces exiguus ; whilst another form was 

 named by M. de Bary Dematium pullulans. 



Certain it is that the mode of life of these plants is essentially 

 different from that of all other living organisms, and the resulting 

 chemical action is equally exceptional. Most organized beings live 

 and grow by absorbing Oxygen from the air, and setting free 

 Carbonic Acid : so do the Saccharomyces in the first stage of their 

 existence ; but the air of the fluid in which they live is quickly 

 exhausted, and when this happens, they obtain the oxygen essential 

 to their growth, from the Glucose ; and in decomposing the Glucose 

 they set free more Oxygen than they require ; and this uniting with 

 the Hydrogen and Carbon present, forms the various products of the 

 fermentation they occasion. 



There are numerous other microscopic funguses whose minute 

 germs are always present in the air, ready to take their life-growth 

 in the decomposition of saccharine fluids ; such as various species 



