Life-History. 
27 
farthest from the neck of the archegonium give 
origin to the first leaf or frond; one, near the neck, 
to the growing point of the stem; and the fourth to 
hairs. Of the other four cells, one, opposite to the 
stem, develops into the root, one ultimately dis- 
appears, and the other two form the " foot of a 
' structure that remains sunk in the archegonium, 
which has grown so as still to surround the foot 
Fig. 23. Diagrammatic sketch of connection of young Fern with 
prothallus, showing f, foot of young Fern imbedded in hollow 
of enlarged archegonium (a) ; fr, very young frond of Fern ; 
p, prothallus ; r, root of Fern ; rh, root=hairs of prothallus. 
Fig. 24. Young Fern growing from prothallus, showing fr, young 
frond of Fern ; p, lower surface of prothallus ; r, root of 
Fern ; rh, root=hairs of prothallus (slightly enlarged). 
(Figs. 23 and 24). By means of this organ the 
young plant absorbs nourishment from the pro- 
thallus, which, for a time increases in size, but is 
gradually exhausted and withers away, and after- 
wards the young Fern is able to nourish itself by 
its own roots and leaves. 
