1910] STOCKBERGER—TOXIC SOLUTIONS AND MITOSIS 425 
parison of cell activities under a series of abnormal conditions varying 
in intensity. It is well known that in a series of dilutions of a toxic 
substance growth diminishes usually as the concentration increases, 
and the end sought in these studies was to contrast cell activities 
under such abnormal conditions of development. No deliberate 
attempt was made to induce abnormal cell behavior. 
The toxic solutions experimented with were (1) copper sulfate, 
a metallic base which readily ionizes; (2) phenol, a non-electrolyte; 
and (3) strychnin, an alkaloid presumably poisonous to protoplasm. 
First the rate of growth of radicles of Vicia Faba was determined in 
a series of concentrations of copper sulfate ranging from 7/20,000 
to %/500,000, then the number of hours required for growth to be 
reduced to the minimum was next observed in order to determine 
the range within which to choose material for study. Root tips 
grown in the above and intervening concentrations were examined 
at intervals ranging from r to 93 hours. Radicles were also subjected 
to the action of stronger solutions, ”/12, 2/320, for intervals of 3 
to ro minutes, and the cells were examined after a lapse of 3 to 30 
hours. The results indicate that the toxic effect was first felt in the 
kinoplasm of dividing cells, as shown by the loss of function and sub- 
sequent degeneration of the achromatic figure. Large vacuoles 
arose in the cytoplasm, frequently deforming achromatic figure and 
nucleus. Later the entire cytoplasm was disorganized. Develop- 
ment of the chromatic figure was consequently inhibited, but neither 
amitosis nor abnormal mitosis was observed. In the controls in 
distilled water, also, the cytoplasm became vacuolate; some of the 
nuclei were enlarged, and occasionally the formation of the cell plate 
was interrupted. In both copper sulfate solutions and distilled 
water the course of events was arrest of mitosis by loss of functions 
in the achromatic figure, followed by the death and disorganization _ 
of the cell contents. 
The treatment of root tips with solutions of phenol ranging from 
2/188 to 10/94 normal produced enlarged achromatic figures and 
caused the cytoplasm to become very coarsely netted or vacuolate. 
The chromatic figure was regularly formed and presented no special 
abnormalities. Neither amitosis nor binucleate cells occurred. 
The chromosomes were normal in number and structure. Spindle 
