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Scientific Proceedings (131) 



are about 1 micron in diameter. In tissue cells they are some- 

 what smaller. The coagulating nucleus in the dying cell, on 

 the other hand, gives a different picture. Here also uniformly 

 sized granules make their appearance but, instead of being 

 evenly distributed, they collect into granular strands which run 

 together to form a nuclear network. 



Another striking death change is a change in the nature of the 

 surface layer of the cell. Neutral Red, injected into a living 

 cell, e. g. y amoeba, a ciliated cell or a starfish egg, colors the 

 cell a rose red, indicating a P H on the acid side. On the death 

 of the cell the color changes to orange. In the relatively large 

 amoeba the Neutral Red may even be precipitated out as yellow 

 crystals. This color change may be explained as follows : 

 Death destroys the impermeable surface layer of the cell, upon 

 which the alkaline environing medium diffuses into the freely 

 permeable coagulated mass and reverses the color of the Neutral 

 Red. 



Another death change which seems to be peculiarly significant 

 regarding the reducing ability of the different components of the 

 cell is shown in the following experiment : When living cells 

 are placed in a solution of Janus Green the mitochondria in the 

 cytoplasm stain a beautiful blue while the nucleus remains color- 

 less. As soon, however, as the cell becomes moribund the dye 

 penetrates the nucleus but instead of staining it blue it gives to 

 the nuclear network a lilac and sometimes a distinctly reddish 

 hue. Janus Green is an oxidation product of diethyl safranin 

 and can be reduced to the red diethyl safranin. In the healthy 

 cell the dye cannot enter the nucleus. When the cell becomes 

 moribund the resistance of the nucleus to the penetration of the 

 dye is diminished and the reducing action of the nuclear sub- 

 stance then becomes evident. When the cell is quite dead this 

 reducing ability is lost and, as more of the dye penetrates, the 

 red color soon becomes masked so that the nucleus finally colors 

 a deep blue. 



The reducing ability of the cell nucleus is also borne out by 

 the reaction of the cell to vital methylene blue. In sublethal 

 doses the readily reducible methylene blue enters the cytoplasm, 

 where it is reduced to J .ts colorless leuco compound. In lethal 

 doses it accumulates in the nucleus so that when the dead cells 

 are exposed to air the nucleus stains more heavily blue than the 

 cytoplasm. 



