42 CYTOLOGY OF YEASTS 



the affinity of the nucleus for dyes depends upon the content of 

 metaphosphoric acid. Perhaps, with a little reservation, we may 

 explain the staining properties of the metachromatin in the same 

 manner. 



With regard to the role of the metachromatin, our knowledge is 

 happily more complete. Certain bacteriologists have tried to connect 

 the pathogenicity of bacteria with their content of granules. They 

 have regarded these as the toxic products of the bacteria or, more 

 definitely, as products initial to the secretion of toxins. This theory 

 was supported by Behring, 1 who pretended to have extracted the 

 metachromatin from Bacterium tuberculosis and stated that this sub- 

 stance corresponded to the toxin of that Bacterium. According to him 

 a gram of this substance on the dry basis will be as toxic as a liter 

 of Koch's tuberculin. It is probable that the metachromatin isolated 

 by Behring was not in the pure state. The investigations of Guillier- 

 mond have indicated that the metachromatin has no relation to 

 toxins, and that it ought to be regarded as a reserve product. . The 

 metachromatic granules are quite abundant during periods of great 

 vital activity in the yeasts. They diminish and finally disappear in 

 old cultures. They disappear very quickly in yeasts undergoing 

 inanition. 



Henneberg 2 has attempted to show that the metachromatic 

 granules are related to fermentation. According to this investigator, 

 it is during the period of greatest fermenting activity that these 

 bodies are most highly abundant in the yeast cell. This is also 

 accompanied with an increase in metachromatin (volutin). The 

 addition of phosphates, which caused a great increase in the ferment- 

 ing ability of the cells, also caused an increase in metachromatin. 

 Henneberg thinks that metachromatin is the zymase itself. Since 

 these metachromatic corpuscles are found in all fungi, Henneberg 

 states that metachromatism may be a general reaction for a certain 

 group of enzymes, just as the guaiac reaction is characteristic for all 

 oxidases. This theory is almost untenable. 



The role of the metachromatin explains itself when the sporula- 

 tion of yeasts is studied. It has been stated that the metachromatic 

 corpuscles accumulate in yeast cells destined to sporulate. They 

 dissolve, and following this, are absorbed by the ascospores, and 

 disappear entirely in the maturity of these cells. (Fig. 47.) They 

 undergo the same evolution as the fats and glycogen, which are 



1 Behring. Congres de la tuberculose, Paris, 1906. 



2 Henneberg, Volutin of the yeast cell. Woch. Brau. 32 (1915), 301-4, 320-3, 

 326-9, 335-7, 345-7, 351-4.. On the volutin (metachromatic granules) in the 

 yeast cell. Cent. Bakt. Abt. II, 45- (1916), 50-62. 



