1904] JOHNSON—MONOCLEA 195 
the same conclusion. It may still be, however, that the unusually 
long neck of the archegonium is of advantage in insuring fertilization, 
as suggested by LertcER (’77, p. 65) and RUGE (’93), though the 
involucre is not so nearly closed at the time of fertilization as they 
apparently supposed. 
The wall of the venter of the archegonium becomes two-layered 
before fertilization. After fertilization, as the embryo develops, the 
venter increases greatly in length and in thickness, forming thus a 
long tubular calyptra which may be twelve or fifteen cells thick near 
the base (figs. 32, 39, ar). This calyptra is ultimately ruptured near 
the top by the elongation of the seta, in such a manner usually as to 
leave it more or less two-lipped. 
THE SPOROGONIUM. 
The actual fertilization of the egg was not observed. At some time 
after the maturation of the archegonium, the neck shrivels at the tip, 
the wall of the venter begins to thicken; the egg then increases in size 
and cell divisions appear in it (fig. 38). 
Material was not available for the determination of the sequence 
of the earliest divisions of the embryo, and from the youngest ones 
seen it could not be discovered whether these were longitudinal or 
transverse. That longitudinal walls appear very early. is evident 
from jig. 36, and the transverse wall near the middle in this figure 
may be the primary one of the embryo, as is usual with other liverworts. 
That there is a quadrant formation in the upper part of the embryo 
Ss evident from figs. 41, 42. 
The differentiation of foot and capsule appears early in the develop- 
ment and is indicated by the more rapid enlargement in diameter 
°f the former and by the larger cells of which it is composed (figs. 
ay 39, 40). The capsule later increases in diameter so as 
ee to exceed the foot, and becomes elongated to eight or ten times 
a. (fig. 31). The seta is developed from just above the con- 
region that first marks the separation of foot and capsule 
Pay od ; ; 40). Later on this constriction is obliterated, the foot 
ee “ <a little in diameter (fig. 31), and the foot is not as sharply 
ScHE vs ‘shed from the rest of the sporogonium as is shown by Gort- 
59, jig. I 7). 
