184 
occurred in the basal portion. These curvatures are slightly notice- 
able in the photographs of my experiments. However, as they extend 
over a considerable portion of the coleoptile, they are not very 
conspicuous. 
In Arisz’s experiments the normal curvature of the basal portion 
was not accompanied by an antitropic curvature of the tip. This 
may be accounted for by the fact that the tip was protected here 
against the influence of the light. The turgescence of this part of 
the coleoptile, therefore, did not undergo any change, and was, 
therefore, perhaps unable to absorb the water expelled in the 
regions below. 
According to this the occurrence of the antiphototropic curvature 
depends in this case on the sensibility being completely or almost 
completely destroyed in the tip, and only partially in the basal 
portion. With an equally intense illumination of the tip the appear- 
ance of an antitropic curvature could therefore not be expected 
when the basal portion of the coleoptile was not illuminated at all, 
or when it was illuminated so strongly that its sensibility was 
completely destroyed, as in neither case a normal curvature could 
appear. I have, however, not had an opportunity as yet to make 
these experiments. 
