168 BOTANICAL GAZETTE [MARCH 
divides but a few times, forming the short stalk. For Riccia 
hirta in particular he says that ‘“‘the basal cell finally divides 
into a single lower cell which remains undivided, completely 
sunk in the thallus, and an upper cell which divides into a single 
layer of cells forming part of the venter.” For Targionia the 
same author says that ‘the basal cell undergoes irregular divisions 
and its limits are soon lost.’’ Strasburger figures and describes 
the basal cell in Marchantia polymorpha as almost or quite super- 
ficial, forming only the stalk. 
The arched ring of cells surrounding the opening through 
which the archegonium neck protrudes at the bottom of the 
dorsal furrow, regarded by Leitgeb as a rudimentary integument, 
appears to be merely the guard cells of the air pore belonging to 
the cavity in which the archegonium grows. 
FERTILIZATION. 
Soon after the ventral canal cell is cut off, the neck canal 
cells break down and the resulting mass extrudes from the tip of 
the neck between the separated cover cells at the bottom of the 
furrow. The pressure being removed from above, the cytoplasm 
of the egg may withdraw slightly from the venter walls and 
round off somewhat, the upper surface always remaining concave. 
The egg fills about three-fourths of the venter cavity. The 
shrinkage is not nearly so much in the healthy egg of Ricciocar- 
pus as is figured in texts for Riccia, only degenerate archegon'@ 
having eggs so much shrunken (fig. 26). Sperms swim to the 
archegonium through the small quantity of water held in the 
furrow, which acts as a capillary tube whose ends dip to the 
water level. Numerous sperms were observed entangled in the 
mass extruded from the neck of the archegonium. The male and 
female nuclei were seen in various stages ‘of fusion neat the 
center of the egg (jigs. 23-25). The diameter of the male 
nucleus is about one-half that of the female nucleus, and at the 
time of fusion stains darker because the chromatin elements wi 
crowded more closely together. The male nucleus presses in 
the side of the membrane of the female nucleus until almost 
completely imbedded. 
