I.] YEAST. 5 



will be observed that the fluid contains neither Protein nor 

 Cellulose, nor Fat, though it does contain the elements of these 

 bodies arranged in a different manner. It follows that the 

 Torula must absorb the various substances contained in the 

 water and arrange their elements anew, building them up 

 into the complex molecules of its own body. This is a 

 property peculiar to living things. 



The Torula being alive, the question arises whether it is 

 an animal or a plant. Although no sharp line of demarcation 

 can be drawn between the lowest form of animal and of veget- 

 able life, yet Torula is an indubitable plant, for two reasons. 

 In the first place, its protoplasm is invested by a continuous 

 cellulose coat, and thus has the distinctive character of a 

 vegetable cell. Secondly, it possesses the power of construct- 

 ing Protein out of such a compound as Ammonium Tartrate, 

 and this power of manufacturing Protein is distinctively 

 a vegetable peculiarity. Torula then is a plant, but it 

 contains neither starch nor chlorophyll, it absorbs oxygen and 

 gives off carbonic anhydride, thus differing widely from the - 

 green plants. On the other hand, it is, in these respects, at 

 one with the great group of Fungi. Like many of the latter, 

 its life is wholly independent of light, and in this respect, 

 again, it differs from the green plants. 



Whether Torula is connected with any other form of 

 Fungi is a question which must be left open for the present. 

 It is sufficient to mention the fact that under certain circum- 

 stances some Fungi (e. g. Mucor) may give rise to a kind of 

 Torula different from common yeast. 



The fermentation of the sugar is in some way connected 

 with the living condition of the Torula, and is arrested by all 

 those conditions which destroy the life of the Torula and 

 prevent its growth and reproduction. The greater part of the 

 sugar is resolved into Carbonic anhydride and Alcohol, the 

 elements of which, taken together, equal in weight those of the 



