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L. LENORE CONOVER 



ting light at its open end and in a direction parallel with the 

 lower, unbent part of the plant shoots. Strong light was sent 

 against the shoot tips by arranging mirrors in a semi-circle for 

 the lower half of the path of revolution. In the upper half of 

 the path, diffused light from the sky directly shone into the 

 cylinders. If now light is the cause of the assumption of the 

 transverse position of the shoot, through negative heliotrop- 

 ism, one would expect these experimental shoots to place their 

 tips at right angles to the direction of the light. Instead of 

 this, the tips straightened out the angles already formed, and 

 came into the same straight line as the lower part of the axis, 

 the shoot tips pointing directly toward the light. 



3. A pot with a young shoot beginning to take the horizontal 

 position was revolved for sixty hours on the kUnostat in the 

 dark-room. The axis of the plant was parallel with the hori- 

 zontal axis of revolution. The young shoot straightened its 

 tip and became orthotropic. This result would seem to indi- 

 cate that the plant, when freed from the directive influence 

 of light and gravitation, possesses no inherent epinasty, but 

 does possess considerable autotropism. 



That we have in Asparagus plumosus a reversal of geotropic 

 response related to the stage of development of the plant, is 

 shown by the following results: 



1. If a plant with a young orthotropic shoot is laid horizon- 

 tally in a dark-chamber, the tip of the young shoot invariably 

 resumes the vertical position. The tip is, therefore, negatively 

 geotropic. 



2. If a plant is used with a young shoot recently bent into 

 the horizontal position, and the preparation is so placed that 

 the bent tip of the young shoot is brought into the vertical 

 position, this tip will, after the lapse of an hour or two, regain 

 the horizontal position. 



3. A pot with three young shoots, all about ready to make 

 the horizontal bend was revolved on the centrifuge for 76 hours 

 at the rate of 50 revolutions per minute. The axis of revolu- 

 tion was horizontal, and the axes of the shoots were parallel 

 with the axis of revolution. During the revolution, the tip 



