436 WARREN H. LEWIS 



SEQUENCE AND RAPIDITY OF CHANGES 



The nucleus appeared to be the first structure to show changes, 

 but it was often difficult to tell whether they preceded those in 

 the mitrochondria, especially the mitochondria in the thinner, 

 more peripheral parts of the cell. The changes in the nucleus 

 and mitochondria proceeded, in part at least, concurreijtly. 

 The granules and vacuoles were usually not affected until some- 

 time later. No especial changes were observed in the cytoplasm 

 or in the centriole or centrosphere. The fixed material usually 

 showed, however, that important changes had taken place in 

 the cytoplasm. The stronger the solution of potassium per- 

 manganate, the more rapidly did the changes leading to the 

 death of the cell take place, and it was only with the weaker 

 solution (1 to 20,000 to 1 to 80,000) that the changes were slow 

 enough to follow. With 1 to 40,000 or 1 to 80,000 these changes 

 were prolonged over a period of half an hour before the cell was 

 entirely dead. In strong solutions death occurred in less than 

 one minute, even at room temperature. I have recently 

 observed the same series of changes at ordinary room tempera- 

 ture. Most of the observations, however, were made in a warm 

 box. 



The rapidity of action was dependent also on the thickness of 

 the cells, the process being much slower in thick cells than in 

 thin ones. In general the cells at the periphery were flatter and 

 thinner than those near the explant ; the peripheral cells were the 

 first to show any change and the first to die. A single prepara- 

 tion with extensive growth sometimes exhibited the whole series 

 of changes at a single instant; some of the cells at the periphery 

 were dead, while some of those near the explant appeared normal. 

 The final end was the death of the cell. Different regions or 

 parts of the cell probably cease to function at different times. 

 The loss of color from the mitochondria and from the granules 

 and the changes such as were seen in the nucleus after the addi- 

 tion of potassium permanganate are all indications that the cell 

 is dying. 



