77/ A' IIIU'M 129 



tlic siil)j(>ct ol" the pericarj). Moi-c IVcciiuMitly, Iiowcxcr, it is -ccurt'd 

 (Mitircl\' tlir()iiii;li the coats of tlit' seed. 



The Scrd-codf.s. — Those may con-csijoiid to the coats of the o\ul(', 

 though usually tiie i)riiniiie is found to have (lisa])])('ar('d. When it 

 persists it takes the name of Tegmen, or Endo])leura, the secundine 

 hecomino; the Testa, or Exopleura. Rarely tlie secundine also disa])i)ears 

 and the seed is Naked. The seed will also be naked when ])roduced from 

 a naked ovule. 



Tlir Micropiilc. — When one or both of the coats persists, the point 

 where the foramen, now closed, existed becomes the Micropyle. 



The Aril. — Frecjuently the develoi)ment of a new coat external to 

 the others is induced by fertilization, and this is known by the general 

 name of Aril. If it develop from the chalaza or a lower point, it is called 

 an Arillus, or True Aril; if from the micropyle, an Arillode, or False 

 Aril. 



Dissemination. — The provisions of the seed for securing dissemination 

 are in most res])ects comparable with those afi'ecting the pericarp. 

 Wind-distribution is preeminent, that by fixation to passing bodies is 

 fre(iuent, and that by means of an edible coat is rare. 



Fixation. — The fixation of seeds disseminated without the pericarp is 

 favored by their small size, enabling them readily to enter crevices and 

 cavities, and by peculiarities of surface which fa\()r the same process. 



The large number and importance of medicinal seeds lend great 

 importance to their study by the i)harmacogn()sist, and this is especially 

 true of the histology of all their ])arts. Inasnnich, however, as the 

 subject of histology has been referred to a se})arate ])ortion of the work, 

 we shall here consider only such characters as can be distinguished 

 by means of an ordinary lens. 



The Hilum. — The hiluni is in most cases readily perceptible, but is 

 occasionally found only by minute examination. It is to be studied as 

 to its position, size, form, surface, and color. Its position is sometimes 

 fixed with reference to the form of the seed, as at the larger or smaller 

 end, upon the l)road side or on the edge, as well as with reference to the 

 micropyle, adjoining it, at the ()])posit(> end or at some intermediate 

 ])oint. It is the last-mentioned character which detennines the class 

 of seed as to itstr()])ism (see Ovule). In size the liiluni may b(> a slight 

 point, or it may cover a considerable jjortion t)f the surface. Its form is 

 frequently characteristic, as heart-shaped (Fig. '.M()) or lim-ar and 

 channelled, as in Fig. '.Vi\. Its color fre(iuenlly (lifV(>rs markedly from 

 that of the remainder of the seed. 



