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202. W. H. Brewer on the Motions of Winding Plants, — 
o ¢ oe fa 
, J 
ArT. XXIV.—Some observations on the Motions cA. des | ee 
ing Plants ; by Wu. H. Brewer, Prof. of Chemistry in + 
ington College, Pa. oS ie 
It has long been recognized as a general law, that n plants 4 
during their growth grow towards the light, but all cibotaniea : 
works that have come under my observation, which speak of 
winding plants and tendrils in this connection, speak of them _ 
as forming, practically, an exception to this law, that is, that 
' they turn towards some ‘“‘dark” or “opaque” object. Thatthey — 
do turn towards a solid support has long been observed, the ef 
is undisputed, and the cause of this motion, instinctive as it 
were, towards some solid around which they may twine 
ways been given, directly or inferentially as the absence of light, 
or more properly the opacity or non-luminous character of the 
support. I have been unable to find any account of exper 
ments on this property of certain plants or of certain orgails 
plants further than merely to show the fact, that it exists. — 
During the summer of 1855 I made some ob 
he xists. 
bservations on the 
ecisely 
a slight fall of snow took place which remained a day of ae 
and in a few hours, all the plants which had sprung Up pe dat 
ground and remained perfectly erect until this time, ail ie 
similar observations at other times suggested to me ta 
cause of the motion towards a support was not owing 10 ae 
influence of light, or its absence, but rather to heat, 
elucidate this subject.a series of experiments were made at UV" 
_. NLY,, during the last summer. & | 
' These consisted in the main of presenting a warm 
i and a cold 
. Support to some brian, tj om and then observing if it er : 
 fested any preference. The plants experimented on wel? ©” 3 
ry 
