I.] YEAST. 5 



In this fluid the Torulcz will grow and multiply. But it 

 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 demarca- 

 tion can be drawn between the lowest form of animal and of 

 vegetable 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 constructing 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 



