The President's Address. By Lord Avcbury. 159 



The fruits of water-plants are often lightened by air-filled 

 cavities. The wide dispersal of the Cocoa-nut is greatly due to the 

 air contained in the fibrous coating. 



The form is in many cases adapted to secure dispersal. From 

 this point of view seeds may be divided into various classes : — 



Seeds or fruits with wings, which are carried by wind. 



Seeds or fruits with feathery appendages, carried by wind, and 

 sometimes, as in the Willow, floated by water. 



Seeds in capsules which open at the top, the seeds being jerked 

 out by the wind. 



Seeds or fruits with hooks, which are carried by animals. 



Fruits which are eaten, and the seeds thus carried by animals. 



Seeds which are thrown by the plants. 



To the first category, viz. those with wings, belong mainly trees, 

 as, for instance, Fines, Firs, Sycamores, Maples, Elms, and Birch ; 

 while, though the fruit of the Lime is not itself winged, it is 

 attached to a leafy bract which serves the same purpose. The same 

 is the case with the Hornbeam. In some cases, however, the wing 

 seems intended, by lightening the seed, to enable it to float, as, for 

 instance, in Spergularia meiritima, Alyssum maritimum, etc. 



The next class, those with hairy appendages, is very extensive. 

 To it belong the Willows and Tamarisks, many grasses, Bulrushes, 

 Cotton-grass, Willow herbs, Dandelion, Thistles, and many other 

 Composites, etc., and which occur very commonly on shrubs and 

 trees. 



In the great family of Umbellifers, as a rule, the " carpophore " 

 splits lengthwise, and the two mericarps, each containing a seed, 

 hang loosely by their upper ends to the two whip-like filaments. 

 The dry plants are very elastic, and sway backwards and forwards 

 in the wind, until at last some strong gust tears the mericarps off 1 

 and carries them away. 



Another large series is that in which the seeds are borne in 

 capsules which open at the top, the seeds being jerked out by the 

 wind, as, for instance, in many Campanulacese, Caryophyllacea", 

 Juncacese, and many others. 



In the case of the Foppy the capsule does not open at the top, 

 but immediately below the summit presents a series of little doors, 

 through which, when the plant is swung by the wind, the seeds 

 come out one by one. The little doors are protected from rain by 

 overhanging eaves, and are even said to shut of themselves in wet 

 weather. The genus Cam'panida is also interesting from this point 

 of view, because some species have the capsules pendent, some 

 upright, and those which are upright open at the top, while those 

 which are pendent do so at the base. 



In some species the seeds disperse themselves by creeping or 

 hopping along the ground. In those mentioned last year the 

 bristles or projections merely serve to keep the seeds in a favourable 



