Xe'wcombe, Gravitation sensitiveness not confined to apex of root. 107 
Observation was next made at the end of 2.5 boiirs. The two roots 
which previously were found straight bad now bent ontward 15 ^ 
and 20 0 respectively, while one root formerly cnrved bad wbolly 
straiö’btened. 
Düring all tbese tests. tbe danip cbamber always con- 
tained several centimeters of free water in addition to tbat 
beld in tbe filter-paper lining tbe cbamber; as stated before. niy damp- 
cbambers were closed against tbe loss of water. 
Fig. 5. 
Seedling of Vicia faha. Method of bending when opposed by bar of cork. 
Tbe foregoing resiüt wonld seem to demonstrate tbe geo- 
tropic sensitiveness of tbe part of tbe root bebind tbe apical 
3 mm. Tbere can be no donbt tbat tbe cnrves are not plastic. 
Some, bowever. may besitate to pronoiince against tbe possible 
participation of bydi’otropism and tbigmotropism in producing tbe 
ciu’ves wben tbe cork bars were employed. Such donbters are re- 
feri’ed to my papers on Tbe Bbeotropism of Eoots i) and Tbigmotro¬ 
pism of Terrestrial Eoots 2 ). in wbicb it is sbown tbat, evenin nn- 
Fig. 6. 
Seedling of Vicia faha. Tip kept from bending by 2 bars of cork. 
injured roots of Vicia faba and Cucurbita pepo. sncb ciirves as 
are recorded in tbis paper are never prodnced by cork in con- 
tact witb one side eitber of tbe tip or tbe part bebind tbe tip 
of tbe root. 
To make tbe matter doiibly sure, two otber experinients were 
set up qnite similar to tbe last, except tbat strips of cork were 
brongbt into contact witb botb sides of tbe tip of tbe root. as sbown 
in Fig. 6: Six seedEngs of Vicia faba bad eacb 3 mm of tbe tip 
removed, and tbe seedlings were tben prepared in tbe damp-cbam- 
ber witb tbeir^tips between cork bars as indicated, revolved for 
7 bours at 8 g in temperature 24.5® and tben observed. Only 
1) Bot. Gazette. XXXIII. 1902. 177. 
?) Beih. z. Bot. Centralbl. XVII. 1904. 61. 
