CONTRIBUTIONS TO BOTANY. 
159 
true that in forming; our judgment regarding affinities, we should 
trust to the assimilation of several features rather than to few, 
stUl the precept of Jussieu should he attended to, tlfat the most 
constant elements are to be observed in the principal organs of 
reproduction, especially those of the ovary and seed, and that 
these characters therefore should hold a prior claim over other 
concomitant, more variable, and less important features, in our 
investigations into the mutual relations of plants.* This rule 
appears to have been wholly disregarded, in respect to the Sti/- 
racea, by nearly all the botanists who have written on this 
family. Notwithstanding that the diagnostic features of the 
genera are severally drawn up in a very elaborate and careful 
manner by Prof. A.DeCandolle, in his excellent monograph of the 
order, the differential characters of the tribe Sijmplocece (Prodr. 
viii. 246) and those of the Styracece (p. 259) are confined wholly to 
the dissimilarity in the aestivation of the corolla, the number of 
stamens, and the size of the cotyledons in relation to the radicle : 
no comparison is made of the structure of the ovarium, which is 
so essentially diffei’ent in these two groups ; and although these 
last-mentioned features are respectively given in the generic 
details of Symplocos and Styrax, no inference in an ordinal point 
of view has been drawn from structures so totally distinct, and 
which it is difficult to reconcile under the same category. 
Before I proceed to consider the affinities of these two groups, 
I will offer some details of the structure of their ovary, as well 
as of their fruit and seed. In the Symplocacea we have an 
ovarium composed of five (rarely fewer) carpels completely 
united around a central axis, which is placentiferous in its upper 
portion and continuous with the style, so that the cells are per- 
fect and separated by as many complete partitions, which retain 
their integrity in the ripe fruit. In those cases where some of 
the cells are occasionally abortive, even where only one cell is 
perfected, the remains of the other cells, together with their 
previous axis, may always be distinguished in that portion of 
the paries which is thickened about that line. Hence it con- 
stitutes an essential feature in this family to have a plurilocular 
ovary, the margins of its carpellary leaves being always placen- 
tiferous and united together in tbe axis, so that the cells thus 
formed are complete from the base to the apex. 
On the other hand, in Styracece. we find a central placentation, 
more or less abbreviated, sometimes almost obsolete, which has 
never any connexion with the style, and hence the summit of the 
ovary, in a greater or less degree, is always unilocular ; the pla- 
centa thus generally rises very little above the base of the central 
space, although it is sometimes elevated above the middle of the 
cavity : in all these cases the bottom of this central space is 
