IgIo] STOCKBERGER—TOXIC SOLUTIONS AND MITOSIS 403 
The present investigation was carried out in order to observe the 
process of nuclear and cell division under certain definite conditions 
of physiological experiment with a series of toxic substances. 
Materials and methods 
In this study young seedlings of Vicia Faba were used, as they 
have furnished material for many similar investigations on the 
physiology of the cell and are well known as suitable material for 
the study of cellular activities. Uniform series of seedlings selected 
for the comparative tests were taken from the thoroughly washed 
sphagnum in which they had germinated, and suspended on glass 
rods in such a manner that the radicle for about 20™™ of its length 
was immersed in the solution. New nonsol glass beakers of 300°° 
Capacity were used, and a careful distinction was maintained through- 
out the experiments between those used for the controls and those used 
for the toxic solutions. This precaution was taken in order to avoid 
the possibility of the controls being injured by the residuum of copper 
Which, as pointed out by NAGELI (15), is taken up by the glass and 
may be given off later to contained solutions in quantity sufficient 
to affect seriously the radicles of plants grown therein. 
The radicles were marked with India ink at a point r5™™ from 
the tip just before they were placed in the solution. When not 
under direct observation, the seedlings were kept in a dark cabinet 
in the laboratory at a fairly uniform temperature. The agents used 
Were dilutions made from carefully prepared solutions of copper 
sulfate, strychnin sulfate, and phenol. The controls in the observa- 
tions on growth rate were grown in distilled water. Either triple 
distilled water was used or the water was redistilled from glass just 
before use. Four seedlings were regularly used in each solution and 
their average growth was taken as the basis of comparison. Except 
in a few cases, when one or two tips were dead, four tips from each 
Set of seedlings were prepared for microscopical examination. 
In preparing the material for microscopical study, various modifica- 
tions of Flemming’s fluids were used in killing and fixing. Dehydra- 
tion was followed by imbedding in 53° paraffin. The sections were 
Cut 3-5 w in thickness and stained on the slide with iron-alum- 
hematoxylin, safranin-gentian-violet, or the triple stain. A Zeiss 
