Cuap. V. CONCLUDING REMARKS. 195 
follow the whole process of transformation. The termi- 
nal leaflets of the leaf-climbing Fumaria officinalis are 
not smaller than the other leaflets; those of the leaf- 
climbing Adlumia cirrhosa are greatly reduced; those 
of Corydalis claviculata (a plant which may indifferently 
be called a leaf-climber or a tendril-bearer) are either 
reduced to microscopical dimensions or have their 
blades wholly aborted, so that this plant is actually in 
a state of transition; and, finally, in the Dicentra the 
tendrils are perfectly characterized. If, therefore, we 
could behold at the same time all the progenitors of 
Dicentra, we should almost certainly see a series like 
that now exhibited by the above-named three genera. 
In Tropzolum tricolorum we have another kind of 
passage ; for the leaves which are first formed on the 
young stems are entirely destitute of lamine, and 
must be called tendrils, whilst the later formed leaves 
have well-developed lamine. In all cases the acquire- 
ment of sensitiveness by the mid-ribs of the leaves 
appears to stand in some close relation with the abor- 
tion of their laminz or blades. 
On the view here given, leaf-climbers were primor- 
dially twiners, and tendril-bearers (when formed of 
modified leaves) were primordially leaf-climbers. The 
latter, therefore, are intermediate in nature between 
twiners and tendril-bearers, and ought to be related to 
both. This is the case: thus the several leaf-climbing 
species of the Antirrhinee, of Solanum, Cocculus, and 
Gloriosa, have within the same family and even within 
the same genus, relatives which are twiners. In the 
