464 SIR JOHN LUBBOCK ON STIPULES, 
This is not, however, the only function of stipules, which in 
some species are developed into spines, in others into glands, 
while in some they perform, or assist in performing, the function 
of true leaves. 
In the following paper I propose to describe the form and 
arrangement of the stipules in many species, and the purpose 
they serve in the economy of the plants. 
It will be seen that where stipules are absent there is generally 
some other arrangement for the protection of the bud; and as 
regards the special problem suggested by Vaucher in the case of 
the species of Helianthemum, further study fully confirms the 
suggestion that in those which have broad petioles the petioles 
serve for the protection of the bud, and there are no stipules ; 
while where the petioles are narrow, stipules are developed and 
serve the same purpose. This, then, seems a complete and satis- 
factory answer to Vaucher’s problem. 
RANUNCULACER. 
Caltha.—In Caltha the leaves are simple; the petioles thick, 
flattened or slightly grooved above, and dilated and sheathed at 
the base. In the radical leaves the sheaths are membranous, 
colourless or pinkish, continuous with and connate for some 
distance with the edges of the leaves, then becoming free and 
forming a cylindrical sheath, which at first encloses the crown or 
axial bud of the plant. The sheaths of the cauline leaves are 
much shorter, and become free from the broadly-dilated, triangular, 
and amplexicaul base of the petiole. The sheaths become gradually 
shorter on the upper leaves. 
Thalictrum aquilegifolium, Linn.—The leaves are at least tri- 
ternate ; the base of the petiole is widely dilated and amplexicaul, 
with the margins produced into thin, membranous, entire valves 
or flaps, which surround the stem and at first enclose the bud. 
Every trifurcation of the lamina of the leaf is subtended by mem- 
branous stipular processes, which appear to differ somewhat in 
their origin from the primary sheath. Behind the middle branch 
of the lowest trifurcation is a large obreniform or bifid stipella, 
with rounded lobes; at the other joints of the leaf this organ is 
bipartite. 
In T. javanicum, Blume, the lobes of the primary sheath are 
fringed at the margin and traversed by branching veins. The 
