THE INFLUENCE OF THE PRESENCE OF PURE METALS 
UPON PLANTS. 1 
EDWIN BINGHAM COPELAND AND LOUIS KAHLENBERG. 
Ever since- investigators began to grow plants in aqueous so¬ 
lutions, it has been a frequent observation that the distilled 
water used was in itself more or less injurious. For instance, 
Asehoff (13. 1890; 115), declares “pure” distilled water to be 
poisonous for Phaseolus vulgaris; and Frank (13. 17, 535), 
finds the water he uses to be injurious to Lupinus , though not 
to corn and beans. These statements have called forth replies 
from Loew (14), and Schulze (13. 20, 1891; 236), (the latter 
without experimental proof), who maintained that really pure 
water is harmless, and that contrary appearances are due to 
impurities, such as salts of copper, lead, and zinc, absorbed dur¬ 
ing or after distillation. 
Nageli’s (17) careful study of the subject was edited by 
Cramer and published by Schwendener twelve years after the 
author’s death. Nageli proved conclusively that water in it¬ 
self is harmless, but that various metals in solution in infinitesi¬ 
mal quantities are deadly. The presence of " insoluble ” sub¬ 
stances, such as carbon and platinum, is without effect. The 
most destructive of all the metals that he tried was copper, one 
part of which in a thousand million parts of water was ulti¬ 
mately fatal to Spirogyra. This dilution was so much greater 
than that of ordinary toxic solutions as to convince Nageli that 
1 A list of the authorities referred to in this paper, together with their 
reference numbers, is given at p. 472 following. Each reference is indi¬ 
cated in the text by a reference number; and where a particular page of the 
authority is referred to, the number of the page is also given in the text, 
following the reference number. 
