486 SIR JOHN LUBBOCK ON STIPULES, 
stipules met with in other species. All the lateral nerves of the 
leaf arise from a short one which curves outward and downward 
from the base of the leaf, and runs down the margin of the wing 
of the stem. 
Bentham, “On the Mimosea,’ Trans. Linn. Soc. xxx., 
refers to the stipules; on p. 341 he says, spinescent sti- 
pules are met with in various groups, especially in the Acacie 
Gummifere and Pulchelle, and a few Phyllodineew and others, 
and, as far as has been observed, are always independent 
of physical conditions. In the Acacie Gummifere, whether 
from tropical America, Africa, or Asia, they offer the curious 
phenomenon of an extraordinary development of some of the 
pairs, or sometimes of nearly all of them, assuming the aspect of 
horns of cattle. Such horn-like enlargements are most general 
in dry hot regions; but, as far as the information of collectors 
can be relied on, many of the specimens thus affected are from 
the richest moist forest-regions of tropical America. They 
never appear to affect the whole of the stipules of any one bush, 
varying in degree of development in the several pairs of stipules 
of the same branch, but affecting special forms and tinges of 
colour, from an ivory-white to a livid purple, for each species. 
They are generally hollow, with a small opening, and in America 
at least are usually tenanted by colonies of stinging ants (as 
in the case of the common bull’s-horn Acacia) (see Belt’s 
‘ Naturalist in Nicaragua,’ p. 218). 
The “ stipelle ” sometimes present at the base of the pinnx 
of a compound leaf, Bentham uses as a serial character in his 
subdivision of the genus Mimosa (I. ¢. p. 389). 
In Crotalaria the presence or absence of stipules, their shape 
and position are of systematic value in the subdivision of the 
genus. Tn one series they run down the stem, forming wings as 
in C. stipularia, Desv. 
In Ozytropis union with or freedom from the leaf-stalk serves 
the same purpose. 
In Macheriwm, a large tropical American genus, the stipules 
are often converted into thorns, which may be bent backwards to 
aid the plant to climb (see Schenck, ‘ Beitriige zur Biologie u. 
Anatomie de Lianen’). 
Urban, in a monograph, “ Morphologie der Gattung Bauhinia,” 
in Bericht deutsch. Botan. Gesell. iii. (1885), says :—‘ The 
stipules are always present by the insertion of the leaf, and com- 
