Chap. IV. VITACE^E. 141 



eleven flower-buds, quickly became curved when 

 slightly rubbed; but even this scanty number of 

 flowers rendered the stalk less sensitive than the 

 other branch, that is, the flower- tendril ; for the latter 

 after a lighter rub became curved more quickly and 

 in a greater degree. I have seen a sub-peduncle 

 thickly covered with flower-buds, with one of its 

 higher lateral branchlets bearing from some cause 

 only two buds ; and this one branchlet had become 

 much elongated and had spontaneously caught hold 

 of an adjoining twig ; in fact, it formed a little sub- 

 tendril. The increasing length of the sub-peduncle 

 (C) with the decreasing number of the flower-buds is a 

 good instance of the law of compensation. In accord- 

 ance with this same principle, the true tendril as a whole 

 is always longer than the flower-stalk ; for instance, 

 on the same plant, the longest flower-stalk (measured 

 from the base of the common peduncle to the tip of 

 the flower-tendril) was 8J inches in length, whilst the 

 longest tendril was nearly double this length, namely 

 16 inches. 



The gradations from the ordinary state of a flower- 

 stalk, as represented in the drawing (fig. 10), to 

 that of a true tendril (fig. 9) are complete. We have 

 seen that the sub-peduncle (C), whilst still bearing 

 from thirty to forty flower-buds, sometimes becomes a 

 little elongated and partially assumes all the characters 

 of the corresponding branch of a true tendril. From 

 this state we can trace every stage till we come to 

 a full-sized perfect tendril, bearing on the branch 



