OF FASCICULATED EXPANSIONS. 273 



able is, that in each species the direction appears to be 

 strictly fixed, viz. — from right to left in the French 

 Bean, from left to right in the Hop. Bryonia presents 

 in this respect a phenomenon of which I know no other 

 example ; its tendril suddenly changes its direction in 

 the middle of its course, so that the upper half twines in 

 a contrary direction from the lower. The causes which 

 determine the twining in general, and the particular 

 direction, are very imperfectly known, and purely 

 physiological. 



CHAPTER III. 



OF FASCICULATED EXPANSIONS. 



All the caulinary organs, which are not expanded into 

 foliaceous or petaloid limbs, have a tendency, in certain 

 constant or accidental cases, to form kinds of expansions 

 of a singular nature, and which I call Fasciculated 

 Expansions, extending a little the ordinary use of this 

 term. In these expansions, the branches, peduncles, or 

 petioles, instead of being cylindrical, become spread out, 

 and, as it were, semi-foliaceous, the fibres or nerves re- 

 maining either nearly parallel or converging, or diverging 

 towards the apex, but nearly simple, and not expanded 

 as in the limb of leaves. It might be said that in this 

 mode of vegetation, the fibrous bundles, usually arranged 



VOL. II. T 



