166 HOME STUDIES IN NATURE. 



removed from the earth, the leaves have a tendency to 

 curve backward until the apex touches the roots. Have 

 these spiral threads anything to do with this movement ? 



Over the outer surface of the leaves are curiously 

 shaped hairs. Near the base are long multicellular 

 ones, as seen by c. The hairs gradually become shorter, 

 have fewer cells as they approach the blade of the leaf. 

 Scattered thickly over the blade are short unicellular 

 hairs tipped with a gland, as seen by e. These glands 

 are the secretory organs. 



It is interesting to note the transformation of the 

 hairs. From the long pointed ones we find every gra- 

 dation before they reach the short unicellular ones tip- 

 ped with perfect glands. There are other organs im- 

 bedded in the cellular tissue of the leaf which remind 

 me of the absorbing glands, "or quadriiid processes," 

 found in utricnlaria ; f represents one of these organs 

 highly magnified. 



I commenced experimenting with P. pumila in De- 

 cember. The thermometer stood at 80°, and it contin- 

 ued almost unvaryingly warm until the 10th of Janu- 

 ary. Towards noon of each day it ranged from T5° to 

 80° in the shade. 



December 20th I placed seven house-flies on as many 

 young, healthy leaves of P. pumila. In two hours and 

 forty minutes the flies were bathed in a copious secre- 

 tion, and in three hours and fifteen minutes two of the 

 leaves had folded over the flies, so as to hide them from 

 sight. The remaining five leaves had made little or no 



