THE CYTOPLASM AND ITS DIFFERENT PRODUCTS 41 



trace of metachromatic granules in their cells. On the other hand, 

 by cultivating these yeasts which have been deprived of their granules 

 in media with phosphate, van Herwerden has noticed the immediate 

 appearance of metachromatic corpuscles. A nucleic acid compound 

 is extracted, along with volutin or metachromatin, by dilute alkali 

 from Torula monosa and Saccharomyces cerevisiae. This cannot be 

 obtained from an equal quantity of volutin-free culture. This seems 

 to prove what has been indirectly supported in the past, that meta- 

 chromatin is made up of a nucleic acid compound. No doubt 

 obtains but that the nucleic acid from yeast originally came from 

 the volutin. This nucleic acid is decomposed by a nuclease formed 

 in the Torula cells, in which process the formation of phosphoric 

 acid could be demonstrated. The metachromatin free cultures also 

 contain a nuclease. This is contrary to the opinion of Henneberg 

 who claims that the metachromatin is the enzyme itself. This sub- 

 stance, according to van Herwerden, is probably a nucleic acid and 

 possibly a reserve material. While it may not be indispensable for 

 the growth of the cells it may be of importance in their individual 

 development. It may be related to the fermenting ability by supply- 

 ing small amounts of phosphates 1 which may be liberated from the 

 nucleic acid by the nuclease. 



The metachromatic corpuscles are certainly nitrogenous products, 

 but their exact chemical nature is not completely known. However, 

 after .the investigations of Meyer, Kohl, 2 and Reichnow, 3 it is ad- 

 mitted that they result from a combination of nucleic acids. Kohl 

 regards them as nucleoproteins. Meyer has demonstrated that the 

 histo-chemical reactions of metachromatin resemble those of nucleic 

 acid and that there are other organisms which chemical analysis 

 reveals to have more nucleic acid, as the yeasts and certain bacteria, 

 which contain more chromatin. Kossel has been able to isolate 

 from yeasts a large amount of nucleic acid, and this seems dispro- 

 portionate to their relatively larger nucleus. It is probable that a 

 greater part of this nucleic acid comes from chromatin. Reichnow 3 

 has demonstrated that in Haematococcus pluvialis, which normally 

 contains much metachromatin, this substance disappears and does 

 not re-form when the alga is cultivated in a medium entirely devoid 

 of phosphorus. Nucleic acid is especially rich in phosphorus. On 

 the other hand the researches of Giemsa seem to indicate that 



1 The investigations of Levene and Kossel have indicated the presence of 

 large amounts of phosphoric acid in yeasts. 



2 Kohl, G. Hefepilze, Leipzig, 1908. 



3 Reichnow, E. Untersuchungen an Haematococcus pluvialis. Arb. a. d. 

 Kaiserl. Gesundheitsamte, 33, 1909. 



