168 Dr. W. Seller on some Plants obtained 
useful descriptive character. In our specimen it appears in 
almost all the silicule that have been opened. In DeCandolle’s 
description of the Crucifere, he mentions, as occasional, the pre- 
sence of a stria or a rima in the axis of the fruit-septum ; and as 
far as I have observed, the stria, which may be regarded as indi- 
cating the tendency to the rima or fenestra, occurs generally in 
the species of Cochlearia, This stria or fenestra in the axis seems 
to suggest the idea that the dissepiment im the fruit of the Cru- 
cifere is composed of two portions extended from the opposite 
sides to meet there. And if this be deemed probable, then the 
conclusion would follow that their seed-vessel is composed, not 
of two, according to the received view, but of four carpels. As 
Mr. Brown says he met with one specimen of C. fenestrata in 
which many of the siliculee were three-valved and three-celled, I 
was curious to ascertain if any of those in our specimen presented 
this anomaly, but was disappomted. Mr. Brown does not say 
how the second dissepiment was placed. It is impossible to sup- 
pose that there were two dissepiments parallel to each other. I 
infer then, particularly as Mr. Brown uses the word “ dissepi- 
mentum” in the singular number, that the additional septum 
joined the normal septum in the axis. Mr. Brown’s discovery 
of three-celled pericarps in a cruciferous plant is an encourage- 
ment to botanists to search for the farther anomaly of four-celled 
pericarps among the same; which can hardly fail to occur, if the 
theory of their fruit bemg composed of four carpels or carpellary 
leaves be correct ; for on this view it must be by abortion that 
placentz and a septum fail to appear opposite to the cleft of the 
stigma, at the place in the valves occupied by the carma, when 
that is present in this kind of fruit. Mr, Brown also remarks, 
in his description of the C. fenestrata, that the umbilical cords 
are jomed together at their bases by a narrow membrane. ‘This 
narrow membrane farther illustrates the structure of the fruit im 
the Crucifere. It represents the margin of the interior layer of 
the carpellary leaf stopping short close to the inner side of the 
middle rib, which here enters into the replum or frame of the 
dissepiment, while the dissepiment itself is composed of the outer 
layer jomed with its fellow of the adjacent carpellary leaf and ex- 
tended to the axis. This accords m so far with DeCandolle’s 
account of the structure of the septum in the Crucifere, though 
he describes it in different terms ; he says the septum is formed 
by the reflexion inwards of the epicarps, while the endocarps stop 
short close to the sutwre and produce the placentz. But if there 
be four such shortened borders of the endocarp, two at each 
margin of the septum, as in all silicule with a double row of 
seeds in each cell, then there must have been four original car- 
pellary leaves, two entermg into each valve, and two into each 
ee 
