96 BOTANICAL GAZETTE {auGUST 
concentration, the first indication of approaching death is an 
increase in the redness of the stain, indicating an increase in acidity 
in the cell. After this the red color rapidly disappears, often within 
a few seconds, or changes to yellow and then disappears. In the 
more transparent cells the disintegration and coagulation and dis- 
integration of the protoplast, sometimes preceded by a rather 
sudden plasmolysis, can be observed directly. In these cases the 
protoplasm, which up to this time has appeared under low magni- 
fication to be uniformly stained, suddenly becomes turbid and con- 
tracts into a small irregular mass in the cell or a number of such 
masses scattered over the cell wall. These masses contain all the 
neutral red as well as the phycoerythrin in cases where it is present, 
and in consequence of the increased acidity and the aggregation 
of the protoplasm, these masses usually appear blackish or purplish 
by transmitted light. Beyond question the moment of this change 
is approximately the moment of death. The appearance of the 
cell is completely altered in many cases. Instead of being uni- 
formly red, it now appears nearly transparent, except in cases where 
the cell wall is also colored, and contains one or more blackish 
masses or granules. Following these changes the color rapidly 
disappears from the blackish masses of coagulated protoplasm, 
leaving the whole cell almost transparent and without color except 
in the wall. These changes are most readily followed in the trans- 
parent hairs or hairlike branches which occur on many of the 
Rhodophyceae, where they can often be observed with great clear- 
ness. It seems probable that at least in some cases the neutral 
red is decomposed with loss of color in the course of the death 
changes, but in other cases it becomes yellow before disappearing 
because the alkali of the KCN solution penetrates as the protoplast 
dies. These various changes, the deepening red color of the stain, 
followed by its disappearance with change to yellow in some cases, 
the visible disintegration and coagulation of the protoplast, and 
finally in the red algae the loss of the natural color by the extraction 
of the phycoerythrin are very definite and striking, and afford a 
means of determining with a considerable degree of exactness the 
time of death of different cells of the plant and so their relative 
susceptibility. 
