34 STRUCTURE AND LIFE-HISTORY OF HAY-SCENTED FERN. 
of the sporangium nearly touches the stalk. Meanwhile some spores have 
fallen out, others remain in each half of the sporangium. Then suddenly 
the annulus springs back to its former place, throwing its load of spores 
several centimeters. Straightway it begins slowly to bend back again, 
and repeats the operation. The springing of the thin walls during both 
the extension and the recoil of the annulus throws out several spores. 
GAMETOPHYTE. 
Spores sown on moist micaceous carth about October 3, 1905, had mostly 
germinated and formed protonemata by the 25th.* About October 1, 
1905, also, fresh male and female prothallia and young plants in various 
stages of development were found in a ravine near Baltimore, Maryland. 
In germination the spore-coat bursts at the tetrahedral angle. The intine 
bulges out, and a cell with many chloroplasts appears (fig. 177). It imme- 
diately sends out a rhizoid which is separated by a wall from the cell. 
Some of my cultures became temporarily dry at this stage, and the first 
rhizoid died. Another was soon sent out from a point farther up on the 
same cell (figs. 191, 193). The protonemata assumed a great variety of shapes 
(figs. 178-199). There were from one to six cells, in linear series. The 
basal cell was sometimes very long and slender (figs. 184, 196), or rarely 
broader than long (fig. 182). The basal cell was usually the longest of all, 
but not always (fig. 197). The growth of the protonema is by transverse 
divisions in the apical cell. Rarely an intercalary division occurs in a 
longitudinal plane. 
Sooner or later the terminal cell divides longitudinally in half (fig. 189). 
One half enlarges more than the other, causing the partition to become 
oblique. Then an oblique wall cuts the larger cell, striking the next 
earlier wall nearly at right angles (figs. 185, 196). The result is a two- 
sided apical cell, which continues to divide parallel to its two sides for a long 
time (figs. 187, 188, 190). The young gametophyte now becomes broader 
at the apex (figs. 194, 195). Soon the cells on either side of the initial 
outgrow those just behind it, and the prothallus assumes its cordate shape 
(figs. 199, 200). The initial is then changed by a transverse wall across 
its posterior end (fig. 203). After this it divides into two longitudinally, 
and we can henceforth recognize only a group of marginal initials (fig. 
200). Each of these cells divides on three sides, viz, two lateral and one 
posterior (figs. 202, 204-207, 214). 
*My cultures were sown in 3-inch to 6-inch flower-pots and pans on micaceous soil 
dug from deep down in a newly exposed bank of earth. Ripe leaves were laid on the 
pots, covered loosely with papers, and allowed to dry and shed their spores. Or, the 
débris of dried fertile leaves was sown. The pots and pans were never sprinkled, but 
were kept standing in 1 to 7 cm. of water, covered with glass plates, before a west 
window of the Johns Hopkins Biological Laboratory. 
