No. 458.] GEOTROPIC RESPONSE IN STEMS. 85 
CONCLUSIONS. 
In conclusion it may be said that both the method of “ alter- 
nating stimulation " and the *after-effect" method as I have 
used them in numerous experiments involving a greater number 
of species than other experimenters have reported, furnish 
remarkably strong evidence that stems respond better to the 
gravity stimulus when their angle of deviation from the normal 
position is one of 90 degrees than when it is one of 135 degrees ; 
and since the question seems to have been narrowed to these 
two angles by earlier workers, it may further be claimed that the 
angle of deviation from the normal vertical position at which 
stems show the strongest geotropic response is one of 9o 
degrees. 
UNIVERSITY OF MICHIGAN. 

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