270 VEGIiTABLE ORGANOGRAPHY. 



and the little process which is observed in the sinus, 

 which results from the incomplete uniting together of 

 the leaflets, is probably the apex of the common petiole, 

 (PL 11, %.l.) 



A very remarkable circumstance of this union of the 

 leaflets is, that every time it takes place the leaflets 

 thus united and transformed into a single limb have no 

 articulations ; we see this in Bauhinia. This circum- 

 stance tends also to connect intimately compound with 

 simple leaves. 



Thus a compound leaf may appear simple, either 

 because all the lateral leaflets are abortive, or because 

 the common petiole is so short that the leaflets appear 

 to be leaves springing in a bundle from the stem, or 

 because the leaflets are united into one limb. 



But are the leaves which are called simple any thing 

 more than compound ones, with united leaflets ? One 

 might be inclined to believe that this manner of expres- 

 sion approaches the truth nearer than the usual one ; 

 but we know that it is hazardous, and luckily useless, 

 to establish an absolute opinion in this respect, provided 

 that we see that the thing is possible, and that it surely 

 takes place in several cases. This theory is especially 

 applicable to palminerved or peltinerved leaves, which 

 only seem formed by the junction of several palmate or 

 peltate leaflets ; but as all these leaflets have the limb 

 penninerved, this remarkable law results, — that all the 

 leaves of Dicotyledons may one day be considered as 

 pinnate limbs, differently joined together. 



