580 
POPULAR SCIENCE REVIEW. 
Glumal Alliance^ and the last three orders^ which form the 
whole of his Alismal Alliance^ are regularly wanting in raphi- 
des. And thus this extensive and characteristic deficiency 
returns^ like a circle^ into itself; analogous to what takes 
place with other and higher characters in the classifi- 
cation of the vegetable kingdom. Proceeding through the 
flowering plants^ in lineal series^ the whole of the Aral 
Alliance proves pregnant with raphides ; the succeeding, 
or Hydral Alliance, barren of them ; while they appear 
again in the Narcissal Alliance. And when we observe the 
curious exception of the exraphidian Acorus among the 
raphidian Orontiacece, it must be borne in mind that this 
plant belongs to the last and distinct section of the order; 
and though admitted by Professor Babington under another 
raphis-bearing order, Aracece, Acorus stands in Professor 
Lindley^s School Botany as the type of a different order — 
Acoracece — there placed between the two orders Juoicacece and 
Juncaginacece, both of which, like Acorus, are destitute, or 
nearly so, of raphides. 
The Dictyogens, so regularly affording raphides, stand 
between the two groups, Alismales and Gymnogens, wanting 
in raphides. The Yams, an order of Dictyogens, have been 
shown to possess, in some very important points of structure, 
no obscure resemblance to the Birthworts, an order of Dicoty- 
ledons. If, however, we compare the cells in the leaves and 
other parts of a Tamus and Aristolochia, the abundance of 
raphides in the former plant, and their absence in the latter, 
will present a remarkable difference not hitherto noticed 
between these orders. 
Of the Exogens, in lineal sequence, the order Vitacece is com- 
pletely isolated, by the possession of the raphidian character, 
from its congeners. The last and least order of the Berberal 
Alliance, Gyrillacece,!^ the only one of whichihave not examined 
species. In the very centre of this Berberal Alliance, which con- 
sists altogether of no less than seven orders, stands Vitacece; and 
in no plant of which Alliance, excepting this single order, have 
I yet been able to find raphides, while in every species which I 
have examined of Vitacece raphides were abundantly found. And 
so, too, taking it in the middle of its circle of affinities, as set 
down by Bindley, this order still presents the same difference. 
Thus, we have a good example of the diagnostic value of the 
raphidian character in exotic Bxogens. And this is not the 
only interesting result of this examination of Vitacece; for 
Leea is now found, in the possession of the raphidian 
character, maintaining its affinity with the order, and 
so helping to justify Adrien de Jussieu and Bindley in still 
retaining that genus in its old place, notwithstanding the 
