TWINERS AND CLIMBERS. 203 



sionally making a complete turn, or loop. This 

 habit has been noticed also in other species. 



Two of the commonly cultivated climbing annuals- 

 are leaf-climbers. These are Maurandia Barclayana 

 and Lophospermum scandens. No special feature neces- 

 sary to be noted here was developed in the experi- 

 ments on these plants, but they are mentioned chiefly 

 on account of the facility with which they may be 

 cultivated by those who may desire to repeat these 

 observations for themselves, and trace all the pheno- 

 mena of leaf-climbing. 



The little fumitory (Fumaria officinalis) is also a 

 humble example of a climber of this kind (fig. 28). 

 Some of the petioles were determined to be sensitive 

 to touching, and responded thereto in about an hour 

 and a quarter. The young internodes forming the 

 germinal shoots of the stem and branches are in 

 constant rotation. The leaves also have their own 

 special spontaneous movement. As this plant is a 

 common weed there need be no difficulty in verifying, 

 and even supplementing, the observations already 

 made. The Corydalis is a closely allied plant, but 

 not so common ; it is intermediate between leaf- 

 climbers and tendril-bearers, with some of the habits 

 of both (fig. 29). 



The plants which climb by means of the develop- 

 ment of the tips of the leaves into hooks, are so few, 

 and those are exotic, that we may dismiss them with 



