108 DIFFUSION- VACUOLES 



more rapidly will the cells die. If now half a unit 

 more of alkali is added to the jelly, or two or three 

 more degrees of temperature are tried, diffusion- 

 vacuoles will gradually make their appearance in all 

 the cells. 



For instance, "red spots" are readily produced 

 in leucocytes. Any jelly which has the correct index 

 of diffusion for a coefficient of diffusion of 12 will 

 cause them to appear if another drop of alkali is 

 added to the jelly. The diffusion of the stain must 

 be excessive; but not so excessive as to cause death 

 in a few seconds. It is necessary to hit off those 

 amounts of alkali and heat which will cause liquid 

 to pass into the cells, but which will not unduly 

 hasten death by staining the nucleus too rapidly. 

 If this is done accurately, these remarkable diffusion 

 vacuoles suddenly begin to appear. If the diffusion 

 is still further increased, the cells will burst and 

 become achromatic instantly. The appearance of 

 the diffusion-vacuole may be regarded as the safety- 

 point of diffusion; and it is a signal that no more 

 alkali or heat may be tried, or the cells may burst. 



It is interesting to watch the fate of these vacuoles. 

 Since the substance is diffusing into the cells to excess, 

 this diffusion must cause death in a short time, 

 .even though the cells do not burst. Before this 

 occurs, however, the diffusion steadily increases, and 

 the "red spots" get larger. When death takes place 

 the cytoplasm liquefies slowly, beginning at the. 

 periphery and progressing more and more towards 

 the nucleus. As the cytoplasm liquefies, more and 



