80 



found microscopically that indicated a production of the volutin 

 granules from the nucleus, it was concluded that volutin-granules 

 generated in tlie cell-body and formed a reserve-material from which 

 the nucleus could draw at will. In this way Rkichenow ') e.g. 

 represents in his culture-experiments with Haematococcus pluvialis 

 the colliquation of the larger clumps in the centre (initially on the 

 side of the nucleus) and a breaking-up into smaller granules at the 

 periphery during the growth of the cultures. 



Of late Henneberg ^) went farther than the researchers who 

 admitted volutin to have significance only as a reserve-material. 

 According to him volutin plays an important part in the fermenting 

 process of Saccharomyces cerevisiae. He even inclines to believe 

 that the fermenting enzyme itself is to be found in the volutin 

 and tries to support his view by a series of microscopic experiments 

 tending to observe the abundance of volutin in the yeast-cell and 

 its distribution in the cell-body, together with the fermenting power 

 He found that the yeast-cell during rest bears some spherical volutin- 

 granules and that a dissemination into finer granules, rendered 

 visible at the initial stage of the fermentation, indicates activity. 

 The lower fermenting power (the carbonic acid production was 

 taken as an index of the fermenting power) runs parallel with a 

 diminution of the volutin. In a sugar-solution, as Henneberg asserts, 

 the volutin is recovered. Before discussing Henneberg's results will 

 return to my own investigation. 



It being possible to make volutin-free cultures from moulds 

 and yeast-cells that could be kept alive for a long space of time I 

 put the simple question : Is the presence of volutin indispensable 

 to fermentation ? To answer it it was only necessary to use for 

 the yeast-tests the volutin-free cultures under microscopic control. 



First of all we had to find out whether fermentation can take 

 place without volutin. When this appeared to be actually the case, 

 the next thing of importance was to obtain some quantitative data 

 regarding the relationship between the fermentation of a volutin- 

 containing and of a volutin-free culture of the same age, both 

 cultivated under the same circumstances (except the absence of 

 phosphate in the culture medium). 



For these experiments the rate of fermentation was estimated 

 partly physically, partly chemically. In the first case the carbonic 

 acid produced was collected above mercury; in the second, the 

 reducing power of the remaining non-fermented sugar was determined 



1) I.e. page 71. 



2) I.e. page 74. 



