﻿1903] 



BRIEFER ARTICLES 



365 



between 95 and 98 per cent, of the individuals partook of this motion, 

 some to a considerably more marked extent than others. 



Agreeing with the 



observation of Schaffner for Helianthus, the 



nutation is much stronger when the ground is moist and the air warm 

 and dry. Fig, 4 is taken with the camera facing away from the sun, as 

 is shown by the shadow of the camera itself near the lower left hand 



Fig. 3.— The same group shown in/^. 2, taken in the afternoon, to show strong 

 westward nutation (to the right). 



corner of the photograph. The almost universal sunward (westward) 

 nutation here is strikingly shown. A photograph taken with the cam- 

 era facing westward would have had the same general aspect if taken in 

 the forenoon. 



The nutation 



'folia 



Bidens, as I have determined by a large number of marked plants kept 

 under observation during night and day. Some of these I have watched 

 for many days, as they lay in my path to and from the class-room. 

 Here the maximum eastward nutation is at about 9 A. m. Noon finds 



