VIABILITY OF DETACHED ROOT-CAP CELLS 
L. Knudson 
One can find in various texts the statement that the root-cap cells of 
plants die and are sloughed off, and it is probably the general opinion 
among botanists that the root-cap cells are either dead when they are 
sloughed off or that they die soon thereafter. Thus, in Jost's Plant Phys- 
iology (translation by Gibson, p. 283) the statements concerning the root- 
cap read as follows: ''Its cells are short-lived, but they are constantly being 
renewed. In spite of this renewal the root-cap does not increase in size 
because the older cells die off in front and are cast off as new ones are 
formed." 
That the root-cap cells, when sloughed off, are not necessarily dead or 
short-lived but may persist for many days, seems to be substantiated by 
various observations made by the writer with a number of different plants. 
In view of the increasing attention being devoted to the subject of root 
excretions, it seems desirable to make record of these incidental obser- 
vations. 
The observations here recorded were made primarily on the root-cap 
cells of corn, although similar observations were made with Canada field 
pea. The plants were grown in water cultures under sterile conditions, 
that is, with the roots growing in the entire absence of microorganisms. 
Pfeffer's nutrient solution was used, with the replacement of dibasic potas- 
sium phosphate for monobasic potassium phosphate and with or without 
one half percent sucrose. 
The root-cap cells generally collected at the bottom of the culture vessel, 
appearing as slimy masses, the amount increasing with the age of the culture 
and the cells always being more abundant in the sucrose cultures. The 
cells were sometimes isolated, sometimes in chains of from two to seven 
cells, again in plates, and occasionally entire root-caps were noted. These 
cells were always in a healthful condition. They were well filled with 
protoplasm and each possessed a conspicuous nucleus centrally placed. 
That the sloughed-off cells are not short-lived is borne out by the fol- 
lowing: Various corn cultures, both with and without sugar, were examined. 
When the cultures were forty-five days old, the precipitates in the culture 
vessels were examined and in no case could a dead cell be found. Every 
cell was well supplied with protoplasm, and that the cells were living was 
apparent not only from their general appearance but also from the fact 
that the cells could be plasmolyzed by a glycerine solution and recovery 
followed. 
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