422 On the Fecundation and Development of Marsilea. 
increases between the first leaves. The increasing covering of 
the bud with hairs, and the liability to injury of the young 
vegetative point, render the observation of the further develop- 
ment difficult. But all the facts hitherto observed go to prove 
that the apical cell continues its further evolution in the same 
fashion, even in the growing stem-bud of the old plant. The 
leaves always appear exactly bipartite, somewhat approximated 
on the upper side of the horizontal axis. It is consequently to 
be supposed that all of them, like the first, origmate only from 
the cells of the two upper series which proceed from the apical 
cell, whilst the third series only furnishes the commencement of 
roots and internodial cells. 
This whole process of cell-division therefore shows that the 
first perpendicular wall divides the germ into the primitive cells 
of the stem and root, and that the ideal primary axis of the free 
germ is consequently to be regarded as horizontal. From the 
stem-cell the first septum separates the first leaf, which has the 
import of a cotyledon. The second furnishes a piece which, as 
it only forms, in common with a divisional cell of the root of 
the same order, a parenchymatous body situated laterally to the 
axis, must be regarded, not as a metamorphosed leaf, but as an 
internodial part, like many which subsequently issue from the 
apical cell of the stem alternately with the foundation-cells of 
the leaves. Consequently the first root also, which hes exactly 
in the line of the posterior extension of the main axis of the 
stem, acquires the position and direction of a main root. On 
the contrary, the view that the foot is essentially the aborted 
primary axis, and that the first root and first bud are only ad- 
ventitious organs, is supported neither by the position nor by 
the sequence of the septa in and between the constituent founda- 
tion-cells of the germ. 
The first germ-leaf is situated in the median line of the germ, 
the subsequent ones to each side. Between the first and second 
leaves the divergence is about =i; the rest follow under a 
divergence of 4, whilst the spiral continually becomes closer. 
On the other hand, the division of the apical cell itself passes 
rapidly into an homodromous spiral with a divergence of 4. 
After the second leaf the cell-multiplication no longer com- 
mences with a perpendicular septum, but rather with walls 
directed towards each other laterally. Their development is 
similar to that known to occur in other Fern-leaves. They 
gradually attain to a greater extension, which only reaches its 
term about the tenth or twelfth leaf. 
The prothallium follows the development of the germ itself 
by an independent growth, moulding itself upon the form of the 
germ. At last the rapidly growing leaf bursts it above, and the 
