Toxicity of Copper to Plant Roots 



169 



particularly noted were those at which growth was retarded and 

 at which it was arrested. 



Table XIII gives the data condensed from the experimental 

 records : 



TABLE XIII (a) 



Toxic Effects op Copper upon Boots of Water Cultures 



First experiment (1905) 



Cu in solution 



Indicating lessened toxicity in well water. 



^^''C^fh-T T^ rt rr> 





Fig. 4. — Bean cultures (eighth exp.), showing effects of varying con- 

 centrations of copper in distilled water and in solutions of mixed salts. 

 S. salt solutions; D, distilled water; W, no copper, and .05 to 3. parts per 

 million of copper. 



TABLE XIII (b) 

 Eighth experiment (1905) 



Total 100 pts. per 100,000. 



