143 TENDEIL-BEABEKS. Chap. IV. 



which corresponds with the sub-peduncle one single 

 flower-bud! Hence there can be no doubt that the 

 tendril is a modified flower-peduncle. 



Another kind of gradation well deserves notice. 

 Flower-tendrils (B, fig, 10) sometimes produce a few 

 flower-buds. For instance, on a vine growing against 

 my house, there were thirteen and twenty-two flower- 

 buds respectively on two flower-tendrils, which still 

 retained their characteristic qualities of sensitiveness 

 and spontaneous movement, but in a somewhat lessened 

 degree. On vines in hothouses, so many flowers are 

 occasionally, produced on the flower-tendrils that a 

 double bunch of grapes is the result ; and this is techni- 

 cally called by gardeners a " cluster." In this state the 

 whole bunch of flowers presents scarcely any resem- 

 blance to a tendril ; and, judging from the facts already 

 given, it would probably possess little power of clasping 

 a support, or of spontaneous movement. Such flower- 

 stalks closely resemble in structure those borne by 

 Cissus. This genus, belonging to the same family of 

 the Vitaceae, produces well-developed tendrils and 

 ordinary bunches of flowers ; but there are no gradations 

 between the two states. If the genus Vitis had been 

 unknown, the boldest believer in the modification of 

 species would never have surmised that the same 

 individual plant, at the same period of growth, 

 would have yielded every possible gradation between 

 ordinary flower-stalks for the support of the flowers 

 and fruit, and tendrils used exclusively for climbing. 

 But the vine clearly gives us such a case; and it 



