LfiCT. XI.] CAULINAR AND FOLIAR APPENDAGES. 655 



fascicles are of different sizes, and arranged in a 

 regular series according to their sizes, the largest 

 being towards the convex side of the petiole, and 

 the two smallest, which are more distant from one 

 another than the others, at each angle of the con- 

 cave side ; whereas all are of the same size and 

 equidistant in the tendril. The structure of the 

 fascicles themselves also differs, for, in. the ten- 

 dril, we find three spiral vessels only in each fas- 

 cicle, arranged in one line extending inwards; 

 while in the petiole each fascicle contains from five 

 to nine of these vessels arranged in two or three 

 lines. From these remarks, although we find 

 that the structure of the tendril closely resembles 

 that of the stem and the petiole, yet, it is evident 

 that this organ cannot be regarded as an abortive 

 leaf. The resemblance of the tendril to the stem 

 is even still closer, as far as regards the cutis, for 

 in both we find pneumatic pores, in that portion 

 of it which covers the green streaks ; a fact which 

 suggests the idea that these streaks perform, in 

 both, the functions of the foliar expansion. But 

 the most satisfactory proof of the affinity of all 

 these parts is the fact, that a ypung shoot, which 

 Mr. Knight grafted upon the tendrils of the Vine, 

 succeeded nearly as well as if the operation had 

 been performed on the stem or the branch. This 

 similarity of structure occasionally produces the 

 transmutation of one part into another : I noticed 





