SEASONAL ACTIVITIES OF PLANTS. 



229 



HERBACEOUS 



Total 

 Date — Exposure 



1901. 



Dec. 31 to Jan. 7 + .80 



—2.10 

 Jan. 7 to 14 + .80 



— .60 

 Jan. 14 to 21 +1.10 



—2.60 

 Jan. 21 to 28 + .80 



— .60 

 Jan. 28 to Feb. 4 +2.25 



—4.00 

 Feb. 4 to 11 + ... 



—4.30 

 Feb. 11 to 18 + .50 



—2.20 

 Feb. 18 to 25 + .50 



—1.50 

 Feb. 25 to Mch. 4 +1.50 



—1.20 

 Mch. 4 to 11 +1.80 



—1.70 

 Mch. 11 to 18 +2.40 



— .30 

 Mch. 18 to 25 +3.60 



— .10 

 Mch. 25 to April 1 +7.56 



— .10 

 April 1 to 8 4.70 



STIMULATION AND ACCOMMODATION. 



There yet remains to be considered the stimulative reac- 

 tions and accommodations of the plant under changes in the en- 

 vironmental forces which act upon it. Generally speaking, it 

 may be said that sudden changes in the intensity with which a 

 force acts upon a plant results in stimulation^ and that gradual 

 alterations are followed by accommodations, and that such ad- 

 justments or adaptations may be produced by the long continued 

 uniform action of any external factor. 



A striking example of stimulation followed by accommoda- 

 tion is offered by the sensitive plant, and the well-known re- 

 sponse of this plant to a touch or blow consists in folding move- 

 ments of its leaves and leaflets. In repeating the test of it, per- 

 haps this blow may be given by a drop of falling water, or by a 



