MORPHOLOGY OF THE FEUIT AND SEED 265 



The terms otihotropoiis, campyJotroiioiis, anntropoiis, &c., 

 are applied to seeds in the same sense as to ovules ; conse- 

 quently the hilum, chalaza, and micropyle have the same 

 relations to one another in the seed as in the ovule. Thus the 

 hilum and chalaza are contiguous to each other in an orthotro- 

 pous seed, and the micropyle is situated at the opposite end ; in 

 a campylotropous seed the hilum and chalaza are also near to 

 each other, and the micropyle is brought round so as to approach 

 the hilum ; in an anatropous seed the chalaza is placed at the 

 opposite end to the liilum, while the micropyle and hilum are 

 close together ; in amphitropous seeds the chalaza and micro- 

 pyle are both removed from the hilum, and placed transversely 

 to it. 



Almost all seeds are more or less enclosed in a pericarp, the 

 only real exceptions to this lavif being in Gymnospermous plants, 

 as already referred to under the head of the Ovule ; and hence 

 the division of Phanerogamous plants, as already noticed, into 

 the Gymnospermia and the Angiospermia. The means of 

 distinguishing small fruits from seeds have been also already 

 described. 



Forms of Seeds. — Seeds vary much in form, and, in de- 

 scribing these variations, similar terms are emploj'ed to those 

 used in like modifications of the other organs of the plant. Thus 

 a seed may be rounded, as in Nasturtiwrn (fig. 578) ; ovoid, as 

 in Polygala (fig. 585) ; oval, as in Asclepias (fig. 582) ; obovoid, 

 as in Delphinium (fig. 579) ; reniform, as in Papaver, &c., &c. 



Structure of the Seed. — 1. The Integuments or Coats. — 

 There are two seed-coats or integuments. These have been 

 variously named by botanists ; the terms employed in this 

 volume, and those most frequently used, are, testa or episperm 

 for the outer coat ; and tegmen or endopleura for the inner. 



a. Testa, Episperm, or Outer Coat (fig. 577, te). — This in- 

 tegument is formed from the primine of the ovule ; in some 

 seeds, as in those of Acanthodium, it has in addition a coating 

 of hair-like cells which are pressed closely to the surface of the 

 seed by a layer of mucilage ; if such seeds be moistened with 

 water, the muoOage which confines them becomes dissolved, 

 by which the hairs are set free, and then branch out in every 

 direction. 



Colour, Texture, and Surface of the Testa. — In colour, the 

 testa is generally of a brown or somewhat similar hue, as in the 

 Almond, but it frequently assumes other colours ; thus, in some 

 Poppies it is whitish or yellowish, in others black, in the Indian 



