The President's Address. By Lord Avebury. 301 



The seeds in some species resemble small beetles, such as Lady- 

 birds, and may perhaps be carried by birds (plate IV. figs. 12a, 126). 



In Mercurialis perennis the capsule is hairy and may easily be 

 carried away with the seed by rabbits and other animals. 



The Box lives on chalk hills, and the seeds are also probably 

 transported in the same way. 



EmpetracE/E. — Empetrum, the Crowberry, is a low heath-like 

 shrub. The fruit is a drupe ; it is 6- to 9-celled with a seed 

 in each cell. The walls are in two layers : the inner (endocarp) 

 is thick and bony ; the outer one fleshy. When ripe the fruit is 

 black, globular, and about the size of a pea. 



CALLlTRiCHlNEiE. — Callitriche is an aquatic floating herb. 

 There is no perianth. The fruit is entire, with a single seed. 



Urticace.e. — The fruit is small, dry, rarely succulent (the 

 Mulberry), 1- seeded. We have three genera ; the Nettle, the 

 Pellitory, and the Hop. 



In the Nettles ( Urtica), the fruit consists of a minute nutlet, 

 inclosed in the persistent calyx, which bristles with short stiff 

 hairs, and thus probably adheres to the feet and fur of animals. 

 The fruit of the Pellitory (Parietaria) is formed on the same plan. 



In the Hop {Humulus Lwpulus), the achene is broadly ovoid 

 subcompressed, smooth, and somewhat glossy. The seed con- 

 forms to the interior of the achene, and the embryo is coiled up 

 so as to fit itself in. Each fruit is inclosed by the incurved base 

 of a large membranous bract, more or less densely covered by 

 yellow glands. The large and light catkin is readily blown about 

 by the wind, which is evidently the principal agent in the dis- 

 semination of the seeds. 



UlmacEvE. — Ovary, 1- to 2-celled. Fruit, a samara or a 

 nut; 1-seeded; seed inverted. In the Elm {Ulmus montana), 

 the ovary is 2-celled with one ovule in each cell, only one of 

 which, however, develops into a seed. The fruit is a samara, flat, 

 thin, and leaf-like, slightly thickened at the centre, broadly ovate 

 or orbicular, six to nine lines long, with a notch at the top. The 

 seed is suspended in a small cavity near the centre of the fruit. 

 The trees flower in February and March, before the leaves appear. 

 The fruit ripens, detaches itself, and is carried away by the wind 

 in June. The wing develops on both sides, from the base of the 

 calyx, along the stalk of the fruit, and the fruit itself, to the style, 

 beyond which it extends on both sides. 



AMENTACEyE. — The ovary may be 1- or several celled, but the 

 fruit is always 1 -celled, and is either a nut or a several-seeded 

 capsule, opening with two valves. The catkin scales sometimes 

 form an involucre, around or below the fruit. 



The wide distribution of the order over the world indicates 

 great antiquity. The anemophilous character of the flowers and 

 their independence of insects tend to corroborate this view, while 



