126 MORPHOLOGY AND LIFE-HISTORY OF YEASTS. 



together. These cells form a new and special generation, which 

 Will terms the first generation of true film cells, since with 

 their appeai-ance the formation of the film begins. In addi- 

 tion to these there quickly form other cells, which are char- 

 acterised by considerably thicker membrane and an abundant 

 content of glycogen and fat. These prove to be true permanent 

 cells, both on account of their anatomical structure and their 

 physiological behaviour, since they alone retain vitality and are 

 capable of development when the cultures are old and all the 

 other cells and the film have perished. The yeast ring, which 

 grows about the same time, is specially rich in these perma- 

 nent cells. They soon produce highly elongated, sausage- 

 shaped or tubular cells, which in turn behave in a similar 

 nlanner and also produce analogous lateral daughter-cells, the 

 result being the formation of many -member ed chains of the 

 kind shown in Fig. 132. Will terms the members of these 

 bands, film cells of the second generation. The older the film 

 the more luxuriant do they grow, and the farthei' do the film 

 cells of the first generation retire to the background. At a 

 later period, partition walls are formed — more or less abun- 

 dantly in the different species — in these elongated cells ; and 

 similar septa are also found in the chains of buds resulting 

 from the germination of the permanent cells in woi't. A view 

 of these is given in Fig. 139. 



These chains of elongated cells partake of the character 

 of an articulated mycelium. The capacity for producing such 

 was first positively demonstrated by Hansen, and proves that 

 the SaccJiaromycetes belong to the Mijcomycetes, or Eumijcetes 

 with septate mycelia. Their position within this sub-kingdom 

 was then, as already stated, indicated by their capacity for 

 producing ascospores, which will be discussed in the next 

 paragraph. In coloured nutrient media, such as beer wort and 

 wine, the progress of film development is accompanied by a 

 bleaching action, i.e. the disappearance of coloui'ing matters. 

 In this manner the colour of a wort can be slowly changed from 

 dark brown to straw yellow. 



The film cells also differ strongly in their chemico-physio- 

 logical behaviour from those of the sedimental yeast. The latter 

 still develop in presence of an extremely low oxygen tension, 

 and devote their chief energy to the decomposition of sugars. 

 On the other hand, the metabolism of the film cells is indis- 

 solubly connected with the presence of a copious supply of 

 oxygen. According to the results of investigations conducted 

 on this point by B. Raymann and K. Kiiuis (I.), they oxidise, 

 to carbon dioxide and water, the alcohol continuously formed 

 in the fermenting underlying solution, and degrade the albu- 

 minoids therein to amides and ammoniun salts of organic 

 acids. Formic acid and valerianic acid are also formed. Hence 



