Newcombe, Gravitation sensiviteness not confined to apex of root. 103 
Thirteen seedlings had 2.5 mm excised, were revolved 
at 8 g for 8 hours, and then showed 4roots with outward curves 
of 10° to 154 The other 9 roots remained straight. In both 
this and the preceding experiment all roots elongated after 
beheading. 
These 2 experiments indicate very clearly that with 2.5 mm 
of the root-tip removed, the root has in most cases lost the ability 
to respond to the centrifugal force, while that ability is retained 
generally when only 2 mm are excised. This lessening of the 
response, must depend, if the curves are geotropic, on the relation 
between the autotropism of the root and its geotropism, the latter 
being reduced either by an increasing inhibition from more proxi¬ 
mal wounding, or by a greater loss of sensory tissue, or by the 
Operation of both factors. 
Pisum sativum. Fifteen seedlings had each 2 mm of the 
tip removed, and were revolved on the centrifuge at 7 g to 8 
g for 14 hours. Ten roots curved outwards forming angles of 
10<^ to 30°, one root bent inward, two bent obliquely and two 
grew straight. 
Forty-two seedlings with 2.5 mm of the root excised, re¬ 
volved at 8 g for 8 hours, show^ed 13 roots bent outward at angles 
from 10° to 30^, and 3 roots bent irregularly, the remaining 26 
roots being straight. 
Five seedlings had 3 mm cut from the tip of the root, were 
revolved at 8 g for 19 hours, and then showed 4 weak outward 
curves of 10^ to 15^, and one weak inward curve. 
The teaching here is the same as for Zea mais. When only 
2 mm were excised the responses in the same period were 
proportionately more than twice as numerous as when 2.5 mm 
were excised. 
The result when 3 mm were excised cannot be compared 
directly with the others, for the period of revolution was more than 
twice as great. The angles attained here were, however, considerably 
weaker than in the other experiments. However, the result shows 
that with even 3 mm of the tip removed, the roots still have the power 
to respond to centrifugal force. 
Lupinus albus. In a total of 37 seedlings, from whose roots 
2 mm had been cut, revolving at 8 g for 6 hours, 13 bent outward 
(unfortunately my notes fail to give the angles), 4 bent irregularly, 
and 20 grew straight. 
In a total of 34 seedlings from whose roots 2.5 mm 
had been cut, revolving at 8 g for 7 hours, 10 bent out¬ 
ward at angles from 10 ^ to 60 o, 2 bent irregularly, and 22 grew 
straight. 
The results here given do not certainly show that a grea¬ 
ter inability to respond to centrifugal force is manifest the 
greater the amount of the root excised. Farther experiments 
are needed. 
Phaseolus muUiflorus. Only 8 seedlings were used to test 
the effect of removing 2 mm of the root-tip, and these gave only 
