14 ON LEMNACE/E AND THE RAPHIDIAN CHARACTER. 
To the same effect were the results of my experiments, formerly re- 
lated, in which raphidian and exraphidian plants, grown from seeds in 
one pot of identical earth, produced and preserved these characters re- 
spectively from the very seed-leaves onwards. Surely the whole facts 
are cumulative evidence of the intrinsic connection of raphis-bearing 
with the cell-life of the species. 
In short, as regards the Duckweeds, while Lemna trisulca and L. 
minor never fail to produce a good crop of raphides, these crystals are 
as regularly scanty in L. polyrrhiza and L. gibba, and so constantly 
absent from Wolffia arrhiza as to afford an excellent diagnostic cha- 
racter between this plant and Lemna minor. 
But there are Orders of plants, both native and foreign, as more 
particularly explained by me in the fourth volume of the * Popular 
Science Review,’ truly distinguished as raphis-bearers; that is to say, 
Orders of which every true member yet examined has been found more 
or less pregnant with raphides, while the species of the next and nearest 
allied Orders are as regularly exraphidian. This phenomenon I have 
verified so repeatedly in our own flora as to leave little doubt so far on 
the subject. For example, in Onagracee we have thus a raphidian 
rder; while, on the contrary, in Hydrocharidacee we have an ex- 
raphidian Order standing between its allied Orders which are not less 
constantly abounding in raphides 
Endless confusion, however, will continue, unless we carefully bear 
in mind the difference between true raphides, spheeraphides, and crys- 
tal prisms, as described in the ‘ Popular Science Review ’ already cited. 
Thus, for want of such care, the spheraphides which abound in some 
Tetragoniacee, Chenopodiacee, and Haloragacee,—beautiful examples 
of which crystals I have described in Sesuvium, Atriplex, Chenopodium, 
Loudonia, and Haloragis, as well as the crystal prisms in the bulb- 
scales of certain Onions, often noticed in my papers,—are still some- 
times objected to my description of these plants as exraphidian. 
Again, the familiar sphzeraphides and prisms of Cactacee are not true 
raphides; neither are the spheraphides and spheraphid tissue (Ann. 
Nat. Hist. for Sept. 1863, plate iv. fig. 13; and Aug. and Nov. 1865) 
of Veratrum, Lythrum and Geranium, Aralia and Rhamnus. 
Discovery of the Raphidian Character in Systematic Botany.—The 
account of raphides in the forementioned number of * English Botany ’ 
contains several errors, most of which may have been the compositor’s 
