310 
L. KNUDSON 
Since in these experiments seedlings were transplanted to the culture ves- 
sels at the outset, and since some of the root-cap cells were sloughed off 
immediately, it seems fair to conclude that at the time they were examined 
some of the cells might have been forty-five days old. 
In the case of Canada field pea cultures similar results were noted, and 
even more striking results were obtained as a result of an experiment. In 
two sucrose cultures (one half percent sucrose) with Canada field pea, all 
detached root-cap cells were found alive at the end of fifty days. To test 
further the viability of the cells, the plants were removed from two of the 
sucrose culture solutions and the solutions were left exposed to the air. 
Various moulds and yeasts developed in the culture solutions, but despite 
the contaminations the detached root-cap cells were still alive at the end of 
twenty-one days more. 
Some of these root-cap cells must have been sloughed off during the 
first days of the experiment, and therefore must have maintained themselves 
alive, after becoming detached, for a period of seventy-one days. It was 
necessary to conclude the experiment in order to examine all the cells, so 
that the maximum period of viability could not be determined. 
Laboratory of Plant Physiology, 
Cornell University 
