Germination of the Seeds of Aquatic Plants. 347 
germination. In most of the experiments the seeds were 
frozen up during successive winters for continuous periods of 
from one to three weeks. 
The fruits of Ceratophyllum demersum germinated but 
scantily in the first year, and freely in the second year, 
about one-fourth postponing the process to later years. ‘Two 
months’ drying promoted early germination. Their capacity 
in this direction was not further tested. 
Sparganium ramosum is conspicuous even among aquatic 
plants for its capacity of postponing germination over a 
number of years. As arule, germination is postponed alto- 
gether to the second year; or, in other words, of drupes grown 
in 1893, none would germinate until 1895. This inference 
applies to mature fruits gathered from the plant, and it is 
based not merely on Experiment 23, but on numerous indica- 
tions displayed in other experiments not included in the 
Table. Experiments 20 to 22 were made on drupes found 
afloat in the seed-drift of the River Thames. A careful study 
of this matter showed that in an average collection of floating 
drupes obtained from the Thames drift in the spring, between 
60 and 70 per cent. were of the previous year’s growth, between 
20 and 25 per cent. of the growth of the year before that, and 
between 5 and 10 per cent. of a still earlier year, which had 
been at least two and a half years in the water. These last 
were usually the first to germinate in the experiments. _ 
Aquatic fowl, however, are important agents in promoting 
the early germination of these fruits. It has long been 
known that water-birds swallow the fruits of Sparganiuwm,' 
which doubtless they sift out of the mud at the bottom of 
ponds and rivers. The stomachs and intestines of thirteen 
wild ducks purchased in the London market were examined 
by me, and in eight individuals occurred 166 stones of a 
Sparganium —to all appearance S. ramosum—the number in 
each bird varying from 3 to 65, and nearly all being entire 
and sound. Such fruits almost all germinated within three 
months when placed in water. In one case two germinated 
within five days of their removal from the bird’s stomach. 
1 Vide the English edition of the Systematic Botany of Le Maout 
and Decaisne. 
