STORAGE OF RESERVES 7-2 



of death of the cell. Similarly, the presence of fat or excessive gly- 

 cogen in the nucleus is a sign of death. There is one substance 

 which seems to be present in relatively unvarying amounts (inso- 

 far as can be judged by the microscope) in all yeast cells irre- 

 spective of the amounts of stored substances in the cell. This is 

 the basophilic nucleoprotein (?) in the centrosome. The hetero- 

 chromatin stain seems to reveal about the same amount in every 

 cell under all different conditions. 



GLYCOGEN 



Meissner (1900) studied the appearance and disappearance of 

 glycogen in the yeast cell and showed that cells filled with glycogen 

 produce more than the theoretical amount of 00^, in fermenting a 

 sugar substrate, because they produce CO2 from their own reserves 

 in addition to that arising from the fermented carbohydrate. He 

 also found that glycogen accumulates in the cell and attains a maxi- 

 mum at the end of the principal fermentation when it begins to dis- 

 appear from the cell, even before all the sugar is consumed. He 

 designated glycogen as a temporary reserve used by the cell through 

 an endogenous diastatic enzyme. He pointed out that the deposition 

 of an insoluble carbohydrate inside a semipermeable membrane en- 

 ables the cell to take in soluble carbohydrate continuously by os- 

 mosis. 



Wager and Peniston (1910) studied the same question with cy- 

 tological techniques. They found that glycogen was deposited in 

 the cell in the form of small granules which coalesced to form a 

 solid mass of glycogen almost completely filling the cell. 



McAnally and Smedley -Maclean (1935) and Smedley -Maclean 

 and Hoffert (1923,1924) showed that both carbohydrates and fats 

 accumulated in the cell as a result of continued feeding with sugars. 

 They found that phosphates increased the deposition of both re- 

 serves and that maltose seemed to increase the carbohydrate re- 

 serve. In addition, they pointed out that an excess of oxygen fav- 

 ored storage of fat. 



Henneberg (1926) also pointed out that the presence of phos- 

 phates favored the deposition of glycogen, while chlorides seemed 

 to inhibit its deposition. He found that the maximal protein con- 

 tent of the cell was 67 per cent but that yeasts containing stored 

 reserves might contain only 22 per cent protein. He stated that 

 the amount of protein in a cell stands in inverse relation to the 

 amount of glycogen (and presumably fat). He pointed out that the 

 yeast cells collected directly from fruits ?re generally rich in 

 glycogen and furthermore that yeasts kept in moist condition on 

 filter paper live longer if they contain large amounts of glycogen. 



Some apiculate and lactose -fermenting yeasts were unable to store 

 glycogen. 



