114 



STIPA. 



[CH. V 



129. After 2 hours dry and weigh them. The peas will be 

 found to have increased in weight, but much less than the 

 control material in experiment 129. 



(131) Stipa pennata. 



The awn of Stipa pennata is, as previously explained \ 

 extremely hygroscopic, untwisting when wetted, and 

 twisting again when dried. To observe its movements it 



Fig. 22. Exp. 131. 



must be fitted up as shown in fig. 22. The awn S is 

 lashed with fine wire to a straight wire above, and below 

 to a hooked wire W : the latter, W, is fixed into the cork 

 C, which is attached underneath the stout paper or 

 cardboard P : in the middle of P is a hole through which 

 the straight wire passes, bearing at right angles the index 



1 Bxp. 118, p. 102. 



