235 
of Pilularia globulifero , L. 
macrospores, lost their power of germination. In order that 
the spores may germinate, it is necessary that they be brought 
into direct contact with water, and in order to facilitate this the 
fruit should be cut open, or if it has spontaneously opened, the 
tough membrane covering the sporangia should be partially 
removed. The fruit is then placed in a vessel of water, and at 
a temperature of from i 8°-20° C.from forty to forty-eight hours 
is usually sufficient for the complete formation of the prothallia 
and sexual organs. It was found convenient, however, in 
many cases to retard the development, and this was readily 
accomplished by keeping the water at a lower temperature. 
In this way it is possible to so regulate the germination that 
all stages can be obtained, a difficult matter where the de- 
velopment proceeds too rapidly. With fresh material the 
spores germinate almost without exception. 
The fruit of Pilularia globulifera , as is well known, is 
a round body about 3 mm. in diameter, at maturity pro- 
tected by a hard dark-brown covering. It contains four 
chambers, each enclosing a single large sorus attached to the 
outer wall. The upper half of each sorus contains only micro- 
sporangia, while the lower half contains for the most part only 
macrosporangia, although sometimes an occasional micro- 
sporangium occurs. At maturity the fruit splits into' four 
parts, but the sori remain covered with the brown membrane 
that separated the four chambers of the unopened fruit, this 
membrane being firm and more or less impervious to water. 
It was possibly a failure to remove this membrane that led 
Arcangeli to mistake the length of time required for the 
germination of the spores. If it is removed so as to allow 
water free access, the mucilaginous cell-walls of the sporangia 
absorb the water with great rapidity, and the spores are carried 
into the water surrounded by a soft mass of colorless jelly. 
Probably under natural conditions germination does not begin 
until the fruit has been open long enough for the covering 
membrane to become somewhat decayed, as the spores retain 
their vitality for months after the fruit is open if kept in 
slightly moistened earth in a cool place. 
R 2 
