SCIENCE-GOSSIP. 



J 95 



in a single half-hour. Godwits had no nests in this 

 dry spot, and reeves were rare. Of course most 

 of the eggs were sat upon ; we did not even touch 

 the nests which contained four, and only took the 

 reeve's nest and a typical oystercatcher's. The 

 birds were frightened away by the shooting and 

 fed in the distance. The field-glass revealed 

 plenty of young avocets among them, mostly 

 families of three following the hen bird, wad- 

 ing and swimming. In one spot the creek 

 looked as if full of lumps of earth ; those lumps, 

 however, were seen advancing and retreating — 

 ruffs at play. As we draw nearer they take to 

 their wings and glide silently away, they are not 

 very boisterous. Then two big birds rise — brilliant 



white with black and brown, the biggest leading. 

 They head for the dunes in the distance, where 

 they have their nest in a rabbit-hole : a shelduck 

 and drake. Little plovers glide over the sand, 

 they run so swiftly that no movement of the 

 legs is visible. We find many nests of them, 

 hollow in the sand, like a terns', with three or four 

 pointed eggs, white, with many black markings. 

 In the same situation we see some avocets' nests, 

 one containing three yellowish long-legged young. 



But, however, we strain our eyes, and, wherever 

 we peer, not a single botkol is seen, nor can we 

 find her eggs — a mystery which mars the enjoy- 

 ment of the otherwise fruitful and interesting 

 day's work. 



WATER-PLANTS AND THEIR WAYS 



By H. B. Guppy, M.B. 



(Continued from page 1S0.) 

 CERATOPHYLLUM DEMERSUM 



A S the space allotted to this paper is limited, I 

 ■^- will dispense with any general remarks 

 concerning this extremely interesting plant. 

 Attracted by the world-wide range of this botanical 

 vagabond, as it has been happily termed, I have, 

 since 1890, made a large number of observations 

 on its habits in various localities, including the 

 Rivers Lea, Mole and Thames, and the ponds and 

 pools of Epping Forest, Wanstead Park and 

 Home Park. These observations have been 

 supplemented each year by numerous experiments 

 in my greenhouse. 



In the first place, we are dealing with a plant 

 that has found its way over the globe, and has 

 reached oceanic islands, like those of the Fijis and 

 the Bermudas, without the aid of marine currents. 

 Its fruits sink in fresh and salt water, even after a 

 long drying. Although in the same fresh-water 

 system it is dispersed by means of floating portions 

 of the plant, my experiments show that in the sea 

 this would be impossible. Stems placed in sea- 

 water sink and decay after one or two days' 

 immersion, and similarly the small pieces that 

 float through the winter in the seed-drift of our 

 ponds and rivers rot in fresh water after a few 

 days' flotation in the sea. It should be noted, that 

 this injurious effect of sea- water not only prevents 

 the plant from carrying the fruit on the stem 

 across the sea, but also deprives it of the power of 

 budding, a process which in this climate is the 

 usual means of propagation in the spring. Nor 

 will drying aid dispersal, as it soon destroys the 

 plant. It can, therefore, be only through the 



agency of birds that Ceratophyllum has crossed the 

 ocean ; and, since the fruits are both too large and 

 too heavy to be conveyed in mud adhering to 

 water-fowl, we must look for them in their 

 stomachs. 



I pass on now to consider the germination of the 

 seed and the conditions requisite for that process. 

 Those interested in this subject will recall the 

 statement in " Syme's English Botany" that the 

 fruit is rarely seen. In consequence, the early 

 history of the plant is not familiarly known, and 

 not all botanists have been as successful as 

 Schleiden, who, after devoting a memoir to the 

 plant, perceived his deficiency in this matter, and 

 subsequently studied the germination to good effect 

 (Linnasa, xi., 513 ; xii, 345). For three successive 

 years only a single mature fruit, grown in a green- 

 house, rewarded my efforts. At length, in the hot 

 summer of 1893, ample materials were obtained. 

 Although the experiments will have to be extended 

 over another year or two, it can be here remarked 

 that under varying conditions, whether in mud or 

 in water, whether exposed to a high temperature of 

 eighty to ninety degrees Fahr. or to a lower 

 temperature of sixty to seventy degrees, whether in 

 the light or in the shade, only about fifteen per 

 cent, germinated during the first year. This plant 

 evidently follows the example of Potamogeton, 

 Sparganium, Calla palustris, and other plants upon 

 which I have experimented, in germinating in 

 scanty numbers during the first twelve months and 

 in postponing the process in the case of the greater 

 proportion of the seeds to the second and third 



