Chapter XIX 



209 



Cytoplasmic Alterations 



that of nuclear autochromatism reported in certain cells whose 

 vacuoles contain anthocyanin (P. A. Dangeard, Moreau, Guillier- 

 MOND). These writers observed that at the moment of death of 

 these cells, the vacuoles lose their color and the pigment becomes 

 localized in the cytoplasm and especially in the nucleus. This phe- 

 nomenon is observed particularly in the final stages of plasmolysis. 



Becquerel advocates the use of a mixture of neutral red and 

 methylene blue. Neutral red stains the vacuoles of living cells and 

 the less penetrating methylene blue colors only the cytoplasm 

 of dead cells. The examination of the cells with the ultramicro- 

 scope, as has been seen, makes it easily possible to determine the 

 moment when the cell dies. 



As soon as death occurs, i.e., the coagulation of the cytoplasm, 

 one witnesses a series of phenomena, 

 designated as autolysis, which consist 

 of an autodigestion of the protoplasm 

 under the action of intracellular proteo- 

 lytic enzymes. The enzymes, whose ac- 

 tion is no longer inhibited, induce modi- 

 fications in the cell, characteristic of 

 degeneration, i.e., cellular necrobiosis. 

 This consists essentially of an autoly- 

 sis, i.e., of a digestion, starting in the 

 interior of the cell itself and instigated 

 by the enzymes. These enzymes, al- 

 though present during life, do not act 

 on living material because of some still 

 unknown mechanism. 



The modifications generally pro- 

 duced in the cell take the form of more 

 and more marked vesiculation of the 

 chondriosomes and plastids, bringing 

 about the alveolar structure described 

 by BiJTSCHLi. The mitochondrial vesi- 

 cles, which are often enormous, sometimes finally burst. Their 

 wall then breaks up into an infinity of small refractive granules 

 which are scattered about in the cell. 



In its turn, the vacuole ceases to exist when the perivacuolar 

 membrane is destroyed. This leads to a contraction of the cyto- 

 plasm which becomes detached from the cellulose wall as if plas- 

 molyzed, and appears as a granular-aveolar coagulum immersed in 

 the liquid of the cell cavity. 



The degeneration of the epidermal cells of Iris during the fad- 

 ing of the flower, involves curious phenomena associated with the 

 chondriosomes and plastids. The plastids (leucoplasts, chloro- 

 plasts and chromoplasts) fill with an infinity of small granules 

 which reduce osmium. These swell and take on the aspect of 

 enormous vesicles. Then the contour of the vesicles gradually 

 loses its distinctness and finally becomes invisible. There remains 

 of the vesicle, therefore, only a mass of lipide globules which have 



Fig. 146. — Tulip. Epidermal 

 cells of red and yellow petals. 1, 

 living and plasmolyzed. 2, dead, 

 plastids vesiculated. 4, myelin fig- 

 ures formed by the cytoplasm dur- 

 ing plasmolysis. M, chromoplasts; 

 N, nucleus; V, vacuole containing 

 anthocyanin. 



