APEX OF THE BOOT IN OSMUNDA AND TODEA. 
99 
Sadebeck recognises among the investigated species two types 
of meristematic structure, the first, represented by S. serpens, 
S. Martensii, S. hortensis, S. viticulosa, has a wedge- 
shaped apical cell, the latter, represented by S. arborescens, 
S. Pervillei (= S. Vogelii, Baker), S. spinulosa, S. Lyalii 
(= S. laevigata. Baker), has a stratified character. Speaking 
generally, the members of the former series are trailing species, 
while those of the latter series of species are more robust. S. 
Wallichii, investigated by Strasburger, is also one of the 
more robust species, and has two wedge-shaped initial cells. 
Thus it appears that a greater complexity of meristematic 
structure is found also in the species of this genus to accom- 
pany a more robust and bulky character. But here again the 
correlation is not very close, though it is clearly recognisable, 
though this is not the case in the roots of the species O. regalis. 
On the ground of the above observations a general conclusion 
may be based which applies, at least for the plants above 
quoted, viz. that though greater bulk of the organ cannot be 
correlated with increased complexity of the meristem in the 
members of plants of the same species (Osmunda regalis), 
still that correlation can be traced in different species of the 
same genus (stem of species of Selaginella), and is clearly 
marked in the members of plants from different genera (roots 
of the series Pteris, Osmunda, Todea, and Angiopteris). 
That the Marattiaceous type of structure of the apex of the 
root is an advance towards those types found among the higher 
vascular plants is recognised by every recent writer on the 
subject. It is interesting to note, however, that the approach 
is rather towards that structure which is found to be charac- 
teristic of the Gvmnosperms, than to that of other vascular 
plants, or even other vascular Cryptogams, such as the Lvco- 
podinse. The coaxial mode of construction, which is dominant 
in the Marattiaceous type, is clearly represented also in the 
roots of the Gymnosperms, while the confocal type is more 
characteristic of the roots of Lycopodium and Isoetes. 
Botanik’ (Schenk), tom. i, p. 244, &c. ; Treub, ‘ Recherckes,’ &c.; Bruchmann 
(ref.), ‘Bot. Centrbl.,’ 1884, No. 46. 
