FIL1CINE7E. 
447 
in Salvinia, they form the free neck-portion (which in Marsilia projects only 
slightly, in Pilularia very much) and the 'closing cells' of the archegonium. Above 
the central cell, the protoplasm of which contracts, a small canal-cell is visible, 
according to Hanstein, penetrating between the ' closing cells,' and behaving as 
in Salvinia. Hanstein was unable to recognise any further cell-formation within 
the central cell, and he concluded that the whole of its protoplasmic body was 
converted into the oosphere ; Janczewski, however, found here also the ventral 
canal-cell which occurs in other Vascular Cryp- 
togams, as a small mass of protoplasm cut off 
from the central cell. After fertilisation the 
layer of tissue of the prothallium surrounding 
the central cell becomes double ; a few chloro- 
phyll granules arise in it, and the outer cells 
grow in Marsilia Salvatrix (Fig. 315) into long 
root-hairs, which are especially luxuriant when 
no fertilisation takes place. In the case of 
Marsilia Salvatrix the antherozoids collect in 
large numbers at the time of impregnation in 
the funnel above the prothallium, and force 
themselves into the neck of the archegonium. 
Development 0/ the Asexual Generation. 
The first processes of division by which, in 
Salvinia^ the oospore is transformed, after fer- 
tilisation, into the embryo, have been most ac- 
curately described by Pringsheim. The first 
division is effected by a wall (basal wall) which 
separates the posterior (hypobasal) half of the 
oospore, above which is the mouth of the 
archegonium, from the anterior (epibasal) half, 
which is usually larger; this wall is nearly per- 
pendicular to the median line of the prothallium. 
The two cells are next divided by walls (trans- 
verse) nearly at right angles to the previous 
one. If the angle enclosed by these two walls 
is bisected by a straight line (Fig. 313, A, c, d), 
this line represents the axis of growth of the 
stem. This is followed by walls (median) at 
right angles to the two former, and thus the 
embryo comes to consist of eight cells, octants 
of a sphere. Of the four epibasal octants, the two upper give rise to the first leaf 
(cotyledon), which, on account of its peculiar form, is known as the ' scutiform leaf:' 
one of the two lower gives rise to hairs, and the other to the apical cell of the stem 
which now lies in front and below {A, v)) in this latter walls are now formed 
inclined alternately upwards and downwards, and by this means the two rows of 
segments are formed out of which the structure of the stem of Salvinia is gradually 
developed. In Fig. 313 ^ are shown, at ///, IV, V, and VI, these segment-cells 
Fig. 315. — Longitudinal section tlirough the spore 
prothallium and embryo of Marsilia Salvatrix 
(X about 60) ; atn starch-grains of the spore, i inner 
coat of the spore burst above into lobes, ex the 
exospore consisting of prisms, c the cavity beneath 
the arched diaphragm on which is the basal layer of 
the prothallium. pt the prothallium, ivh its root-hairs, 
a the archegonium, / the foot of the embryo, 7u its 
root, J the apex of its stem, b its first leaf by which the 
prothallium becomes extended, si the mucilaginous 
epispore which at first forms the funnel above the 
papilla, and which still envelopes the prothallium fifty 
hours after the dissemination of the spores. 
