(5(5 TKANSACTIOXS, NATURAL HISTORY SOCIETY OF GLASGOW. 



inflated arillus with which it is surrounded. By- 

 and-by this too gets waterlogged, and the seed 

 sinks to the bottom. The seed of Naphar luteum 

 is not provided with an inflated arillus as in Nym- 

 phcea. After separating from its stalk, the fruit 

 loses its outer wall, and the disjoined carpels float 

 off in different directions. Air-bells enclosed by 

 mucilage keep the carpel afloat for a longer or 

 shorter period. "When at last its outer covering 

 decays, the air-bubbles gradually escape, the gela- 

 tinous mass slowly dissolves, and, as it drifts, drops 

 its numerous seeds one by one to the bottom. It 

 would be difficult to conceive of a more perfect 

 contrivance for dispersion through the agency of 

 water than this flotilla of rafts by means of which 

 the water lilies strew their seeds far and wide 

 over the bottom of the waters where they grow. 

 The curious fruit of Nehanbium, which consists of 

 an enlarged receptacle in which the nuts are in- 

 serted as in sockets, may also be intended to serve 

 as a raft which shall, by discharging its freight in 

 this piecemeal fashion, secure the wide distribution 

 of the seeds. The fruit of the Indian-cress {Tro- 

 pceolum) is very light in proportion to its size, and 

 that of Valerianella has two empty cells, but these 

 are possibly capable of dispersion by wind. The 

 seeds of Lemna sink and remain below the water 

 during winter, but rise to the surface in spring. 

 Minute bodies, especially those which do not 

 readily become wetted on account of their surfaces 

 having little affinity for water, even if they are 

 heavier than that liquid, do not sink, because the 

 cohesion of the water is not destroyed. This 

 property certainly belongs to several seeds, and 

 possibly to the pollen-grains of Vallisneria. The 

 fringed seeds of Sjoergxdaria, for this reason, can lie 

 on the surface of the sea for a considerable time 

 without becoming wet. Very few seeds, however, 

 appear to be able to resist the action of salt water 

 for any length of time. Still, that some seeds do 



