Curvature of Roots. 429 
mechanical curvature. Its action, however, is less certain than 
that of branding. Thus, in a not particularly favourable case, 
of seven radicles of Vicia Faba cauterized 1, 2, 3, and 4 mm. 
from the apex, three showed the sharp mechanical bend ; the 
others gave no definite result. 
4. Four specimens of Lupinus albus had a fragment of 
metallic copper placed on the slanting side of the apex of 
the radicle and were kept in damp air. Eight hours later all 
were deflected, showing marked traumatropic curvature, which 
was still more pronounced at the end of twenty-four hours. 
5. To four radicles of Lupinus albus were attached, close 
to the apex, a very light and small fragment of filter-paper, 
about 2 mm. square, which was saturated with 96 p. c. 
alcohol. Seventeen hours later, having been left during that 
time in a damp atmosphere, three of the four were strongly 
deflected. 
With two other specimens the experiment was varied by 
using a piece of blotting-paper, about 2*5 mm. square, 
saturated with 96 p. c. alcohol. Seven hours later both were 
strongly deflected. 
6. In connexion with the foregoing, an attempt was made 
to ascertain whether the deflection was induced by the action 
of the alcohol or by the pressure of the paper. That it was 
the former appears from various experiments, among them 
the following: — A thin fragment of glass was placed laterally 
just back of the apex of the radicle of six specimens of Vicia 
Faba . In all six cases the glass continued to adhere for 
twenty-two hours, but none of the specimens showed evidence 
of traumatropic curvature. Thin pieces of mica were em- 
ployed with thirteen specimens of Vicia Faba with the same 
result. Other light objects were used in the same way with- 
out deflection following. 
7. The radicles of ten healthy specimens of sprouting peas, 
the radicles being about 5 cm. long, were held so that the 
tips would touch laterally the neck of a glass flask from which 
steam was issuing. The water had been heated for an hour 
or more. The temperature of the glass at the point where 
