412 BOTANICAL GAZETTE [JUNE 
which would just permit growth in 2/4 and 1/12 solutions as boundary 
concentrations, with results indicating that a slight amount of growth 
would follow exposure to a m/4 solution for three minutes, and that 
seven minutes’ exposure to the 2/12 solution, while permitting some 
growth, was not far from the point of killing. 
For the experimental work the solution 2/12 was chiefly relied 
upon as being best suited to give a sharp toxic effect, without endanger- 
ing the loss of the material through death. The radicles were exposed 
to this solution for periods of three and seven minutes, respectively, 
were then rinsed quickly in distilled water, and at once transferred 
to the medium in which they were kept until the time for killing and 
fixing. Another dilution and longer interval of exposure were also 
employed to furnish a broader basis for observation. 
In order to have at hand for constant comparison material grown 
under parallel conditions with the toxicated radicles, except for the 
treatment with the copper sulfate solutions, a uniform lot of seedlings 
was taken from the germinating chamber, selected to approximately 
the same size, and divided into six groups which were then prepared 
as follows: (a) one group in moist sphagnum;,. (b) one in distilled 
water; (c) one in 2/12 copper sulfate three minutes, then sphagnum; 
(d) one in n/12 copper sulfate three minutes, then distilled water; 
(e) one in m/12 copper sulfate seven minutes, then sphagnum; (/) 
one in 2/320 copper sulfate ten minutes, then distilled water. 
Four root tips were fixed from each series at intervals of 3, 7, 22; 
and 30 hours. Sections of the tips from the first two series, designated 
as the controls in the following pages, were compared at every stage 
with the sections studied in the remaining series. 
The cell growth and nuclear division observed in the controls 
placed in sphagnum were considered as normal, since good prepara- 
tions were secured showing abundant mitoses, all of which conformed 
to the type generally reported as occurring in vegetative tissues of 
Vicia Faba (fig. 6). Departures from the normal cell division were 
observed in the controls grown in distilled water similar to those 
observed in the controls paralleling the cultures in dilute copper 
sulfate solutions (figs. 2a, 2b). Since the radicles in the copper sulfate 
solutions were manipulated under conditions identical with those 
obtaining in the controls, except for the exposure to the toxic solution, 
