APEX OF THE ROOT IX OSMUNDA AND TODEA. 
77 
those cut off below (i. e. from the end next the body of the 
root) take part in the formation of the body of the root, those 
above act as calyptrogen. 
A group of initial cells, having apparently very similar 
characters to the above, but without the formation of a calyp- 
trogen, has recently been described by Bruchmann (ref., ‘ Bot. 
Centrbl.,’ 1884, No. 46), in the stem of Selaginella spinu- 
losa, though it had already been noted by Sadebeck (‘ Schenk’s. 
Handbuch.,’ Bd. i, p. 244). In Selaginella Wallichii 
Strasburger found that two wedge-shaped initial cells occupy 
the summit of the stem. 1 Finally, Strasburger, in his recently 
published ‘ Botanische Practicum,’ gives a drawing (1. c., 
fig. 93) of the apex of the stem of Lycopodium selago, in 
which three cells (marked i) are distinguished as initial cells. 
Two of these are again represented as seen in longitudinal 
section in his fig. 94. A useful summary of different varieties of 
such meristems is to be found in Haberlandt’s ‘ Physiologische 
Pflanzenanatomie,’ pp. 44 — 52. In a note on p. 59 of this work 
the question of the mode of transition from growth with one 
apical cell to that with two or more initial cells is discussed, 
but owing to the want of necessary observations on the subject 
it is only treated theoretically. As yet we have no direct evi- 
dence as to the manner of transition, though, as Haberlandt 
points out (p. 60), the transition must have taken place. It is 
the object of this article to add to the information at present 
at our disposal. 
In a memoir ‘ On the Comparative Morphology of the Leaf 
in the Vascular Cryptogams and Gymnosperms,’ communi- 
cated to the Royal Society, I have pointed out that in various 
characters of the leaf the Osmundaceae occupy a posi- 
tion intermediate between the leptosporangiate Ferns and the 
Marattiaceae. The idea suggested itself that the Osmun- 
1 When it is remembered that Treub found a single wedge-shaped apical 
cell of variable form in the stem of Selaginella Martensii, it will be 
clear that in this genus variations of structure of the apical meristem of the 
stem are to be found which are very similar to those described below in 
the Osmundaceee. 
