302 Proceedings of the Royal Physical Society. 
sink, for the most part did not germinate until the next 
year, and until the third year, as indicated in the Table. 
In some of the experiments the seeds were dried from three 
to five months and then placed in water, the result of which 
was that they germinated freely in a few days. 
The fruits of Alisma plantago, as a rule, do not defer the 
germinating process beyond the first spring. In one experi- 
ment, however, fruits found in the Thames seed-drift in 
November 1892 did not germinate until April 1894. Fruits 
kept dry during a winter germinated but scantily in the first 
year. 
When the freshly-detached fruits of Alisma ranunculoides 
are put in water, some of them germinate in a few weeks, 
but most defer the process to the next year. The effect of 
a winter’s drying—that is to say, of drying for some three 
or four months—is to cause about 20 per cent. of the fruits 
to defer germination to the second year. 
The seeds or fruits of all the four species of Alismaceze 
above referred to, viz., Sagittaria sagittifolia, Damasonium 
stellatum, Alisma plantago, and A. ranunculoides, are able to 
withstand a week or two’s inclosure in ice without any 
impairment of their germinative capacity. 
The seeds of Jris pseudacorus, when placed in water, 
usually do not germinate in any numbers until the second 
year. Hitherto their capacity of deferring germination has 
not been tested beyond the second year. The only experi- 
ment in the Table which comes near in its thermal conditions 
to a pond or river is No. 49. In all the others the large 
number of germinating seeds resulted from the exposure of 
the vessel to very warm conditions. A good proportion of 
the seeds float for a year and more in the seed-drift of ponds 
and rivers, and an average collection of these drift-seeds 
comprises some that have been at least twelve months afloat. 
In the case of seeds gathered direct from the plant and placed 
at once in water, very few, if any, germinate in the first year. 
Out of a collection of seeds obtained from the winter drift 
of ponds and rivers, and placed in a vessel of water, between 
20 and 50 per cent. germinate in the first year under ordinary 
thermal conditions. 
