460 
Copeland and Kahleriberg. 
The asterisk * marks the time when the development of lateral roots 
first seemed likely to affect the growth of the tap root. 
The appearance of the dead roots, exposed to various metals, November 
30, was as follows: 
Cu—the dark greenish -brown of Rookwood pottery. 
Ni—white. 
Co—brown, reddish or bluish in spots. 
Fe—not very dark brown. Stubby lateral roots appeared after the main 
root tip died; these, too, were short lived. The root was covered early in 
the experiment with a brownish coat of “ iron rust.” 
Cd—brown; entirely collapsed above. 
T1—light brownish; flaccid. 
Zn—slightly discolored; lateral roots as with Fe. 
Sb—brownish-yellow. 
Mg—irregular brown blotches nearly covering light colored field; flaccid. 
As—slightly discolored, flaccid; immersed hypocotyl-like root. 
I—tip red-brown; little discolored above, and inclined to form stunted 
lateral roots there. The tip became almost blue as the iodine diffused 
upward, and killed the rest of the root and stained it red. 
W—drab, flaccid; hypocotyl brown. 
Hg—one plant dead, with root white. 
There were seven control plants in four beakers, and only 
one of these showed any considerable divergence (an excess) 
from the average given in the table. They were the first to 
develop lateral roots, which depressed the growth of the tap 
root a little; but the platinum, carbon, and gold cultures soon 
passed them in this respect. A very long tap root does not 
necessarily indicate thrifty growth and is frequently a symp¬ 
tom of disease. The lower part of the tap roots of the bis¬ 
muth, chromium, indium, selenium, tellurium, and surviving 
mercury plants shot out as long, branchless whips, which for 
a time furnished formidable figures for the table, but were 
obviously abnormal and likely to result in death. The plant 
grown with tellurium died abruptly at the end of such a 
growth, and the selenium plant had probably reached its limit 
by the last measurement. On the other hand, the tap root of 
the ruthenium plant became stunted and at the end of the ex¬ 
periment was being passed by two very slender lateral 
branches. The root of the manganese plant was stained pale 
yellow and cracked to let out numerous lateral roots, which 
