36 STRUCTURE AND LIFE-HISTORY OF HAY-SCENTED FERN. 
planes at right angles to one another, and at last irregularly (fig. 230), to 
produce 32 sperm mother-cells. These separate and round off, and in 
each one a spiral spermatozoid develops. As the central mass enlarges it 
pushes itself down into the center of the stalk-cell until it reaches the 
original basal wall (figs. 230, 237). Thus the stalk-cell becomes ring- 
shaped, though at first it was a disk (figs. 226, 229). At maturity the 
contents of the antheridium swell up by absorption of water, the cap-cell 
is ruptured irregularly, and the sperm mother-cells escape. After 45 to 
50 seconds the mother-cell wall bursts and the spermatozoid swims rapidly 
away with a steady rotary motion, bearing a granular vesicle at the pos- 
terior end. From cultures of male prothallia kept free from surface-water 
it is easy to get numbers of spermatozoids by mounting the prothallia in 
water. Mr. W.D. Hoyt found them to be distinctly attracted by a malic- 
acid solution of suitable strength. The body of the sperm makes about 
two and a half coils. The anterior end is more slender and more closely 
coiled. 
TABLE 7.—Development of antheridium. 
Prothallial cell 
Prothallial cat Stalk cell 
Antheridial cell aewesne wall cell 
Body cell ¢ outer cell ) “ cover cell 
inner cell—32 sperm mother cells 
Female prothallia are always cordate in shape and bear their archegonia 
on the under side of a central thickening or cushion. They begin to form 
sexual organs when still narrower than long, five or six weeks from sow- 
ing of spores. If not fecundated they continue to grow larger and broader, 
and produce many archegonia in succession over all the central lower sur- 
face. The upper surface is at first flat, but in old females the margins 
may become reflexed dorsally, and the plant forms a broad, erect funnel, 
open on one side. The largest in my cultures are 5 to 7 mm. tall and 6 
to 9mm. across. I found one out of doors 7 mm. wide and 4 mm. long. 
The archegonium develops from a cubical superficial cell of the pro- 
thallus, near to the initial cells. This cell may be a semi-segment, involv- 
ing half the thickness of the prothallus (fig. 202), or it may be simply 
the outer part of a semi-segment (figs. 206, 214), according to its point of 
origin on the prothallus and the size and thickness of the latter. In any 
case the definitive archegonial mother-cell first cuts off a thin superficial 
cell, the neck rudiment (fig. 202). Then on the opposite side a similar 
basal cell is separated, leaving a large central cell (figs. 206, 207). The 
basal cell divides crosswise into four and forms the innermost part of the 
wall of the archegonium (fig. 208). The neck rudiment similarly divides 
crosswise into four (fig. 207). Its first cleavage wall is parallel to the 
longitudinal axis of the prothallus. Now the central cell enlarges and 
pushes out the four neck-rudiments. As the latter project more and more 
