Germination of the Seeds of Aquatic Plants. apt 
experiment beginning and ending at the same time for 
both plants. It is noteworthy that with these two plants 
germination was more frequent in the room than in the 
ereenhouse. This I attribute to the daily range of the 
water-temperature in the room being much less than that 
in the greenhouse; and in this respect the experiment in 
the room closely reproduced the conditions of ponds and 
rivers.! 
Inclosure in ice and in frozen mud for continuous periods, 
varying from seven to seventeen days during successive 
winters, did not impair the germinating powers of the fruits. 
The effect of freezing on the general course of the experi- 
ments could rarely be appreciated. Im Experiments 37 and 
38 there was no freezing, whilst in Nos. 39, 40, and 41(a) 
the fruits were frozen up for a week or two at a time during 
each winter. 
Sea-water immersion favours rather than retards germina- 
tion. Fruits that had been lying sunk two and three months 
in sea-water freely germinated, even in one experiment where 
the density had been increased by the addition of salt to 
1:050. 
If the postponement of germination had depended on the 
hardness of the seed-case, the fruits of Sagittaria sagittifolia 
would not have been able to defer the process. That they 
can do so is shown in the Table. They are also able to 
germinate freely after a period of drying which, in two 
experiments not given in the Table, covered three and four 
months. They can also withstand sea-water immersion. 
Out of 74 fruits that floated six and a half months in sea- 
water, 1 per cent. germinated in the first year, 60 per cent. 
in the second year, and 10 per cent. in the third year. 
With regard to Damasonium stellatum, it may be here 
stated that the seeds sooner or later escape from the carpels. 
They can rest for a long time on the surface of still water, 
but sink at a touch; and it is remarkable that seeds matured 
in July, and placed at once on the surface of water, readily 
germinated there in a few days; whilst those allowed to 
1 The discussion of the thermal conditions requisite for the germination 
of aquatic plants will be attempted in a future paper. 
