meris terns of Ferns as a Phylogenetic Study . 32 7 
may be drawn from the comparative study of the apices of 
stems in the main series of Filicineae. 
(1) That while the apex of the stem of most lepto- 
sporangiate Ferns is distinctly conical 1 , that of the Osmun- 
daceae and Marattiaceae is flatter, and more bulky. 
(2) That, though in the leptosporangiate Ferns a single 
initial, with definite and regular segmentation, is always 
present, in Osmunda it is not always to be seen, while in 
well-grown plants of Marattiaceae a single initial is absent, 
the growth proceeding from a number (4 ?) of initial cells. 
(3) That the initial cells of the Osmundaceae are narrower 
and deeper than is usual in leptosporangiate Ferns ; in the 
Marattiaceae this is seen in a marked degree, and they are 
even to be found of rectangular form : these facts imply a 
lower position of the centre of construction of the meristem. 
(4) That in the above respects the leptosporangiate Ferns, 
Osmundaceae and Marattiaceae, form a natural series, starting 
from those with a more convex form of the apical cone, 
and with simpler and more diagrammatic segmentation, 
and relatively high centre of construction, and proceeding to 
those with more complicated and less regular segmentation, 
and relatively deep-seated centre of construction. 
(5) That these conclusions as drawn from the comparative 
study of the apices of stems correspond to the conclusions 
drawn from the study of the roots. 
Apices of Leaves. 
As we proceed upwards through the same series of Ferns as 
those above examined for the structure of the apex of root 
and stem, it will be seen that in the character of the apex of 
the leaf also a similar increase in complexity of the meri- 
stematic tissues is to be traced. 
The observations of Kny 2 , of Sadebeck 3 , and of Prantl 4 , 
1 Trichomanes seems to be exceptional in the flatness of its apical cone. 
2 Parkeriaceae, Taf. XXII-XXIV ( = V-VII). 
3 Verb. d. bot. Ver. fur d. Prov. Brandenburg, XV. 116. 
4 . Hymenophyllaceae, pp. 4-7. Schizaeaceae, p. 3. 
