FRUITS AND COLONISATION BY SEED. 37 



animal would touch. In all fleshy fruits, similar modifi- 

 cations for protecting the sugar are to be expected. The 

 Lemon, Citron, and, in fact, the whole Orange family, yield 

 a complete series of these essential oils, and a consider- 

 able capital is employed in their extraction (oil of 

 neroli and oil of orange flowers, etc., are well-known 

 examples ; they are used chiefly in perfumery). The 

 fleshy part of the orange is divided into segments. 

 Each of these segments with the corresponding part of 

 the peel outside itself forms one carpel. The hollow of 

 this carpel is nearly filled by large juicy projections 

 which will be found, on examination, to be attached to 

 the inner wall near the outside ; the seeds, which are 

 near the centre, are smooth, very slippery and tough. 

 Their shape is peculiar and difficult to describe. Half 

 the seed, when it is divided lengthwise and through the 

 widest part, is not unlike that part of a duck's body 

 which is submerged when the bird is in the water. The 

 toughness, the slippery character and the shape of the 

 seed, make it difficult for a bird to hold it : the seed 

 will spring away from the bill, and thus be scattered ; or, 

 if it is by chance swallowed, the same characters will 

 enable it to pass uninjured through the alimentary tract. 

 Within this tough slippery Seed-coat or tes4a are the 

 Embryo Orange Trees of which there are several. Each 

 of them has a very minute tip which is the embryo 

 root, two flat, often unequal-sized leaf-like bodies, which 

 are the Seed-leaves or cotyledons, and between them a 

 minute bud which represents the future stem or shoot. 

 The seed-leaves are oily, and contain food material 

 upon which the embryo lives until its own green leaves 

 are produced. In other cases the seed contains a mass 

 of food material in which the Embryo lies, the whole 

 being enclosed in the seed-coat ; but in the orange the 



