PHYTOGENY. 249 



while the germinal leaflets, or plumula, are the two ante- 

 rior pinnate leaflets, together with the odd leaflet. The 

 seed-rib or vascular cord (raplie) is continued into the 

 seed-rootlet or radicle, and this into the petiole of the 

 cotyledons. 



1313. Every seed-coat must consist of three integu- 

 ments ; for every leaf consists of the lower and upper 

 membrane, and of the interjacent parenchyma, in which 

 the vessels are dispersed. The external leaf-membrane 

 forms the most hard and coloured covering of the seed 

 (testa), the internal the brown seed-tunic or pellicula ; 

 between the two lies the brown fibrous tissue, or desic- 

 cated parenchyma with the vessels. 



1314. The umbilicus is the cause of the bud or of the 

 seed-leaf; the seed-hole or micropyle is on the apex of 

 the involuted bud, or rather of the phyllodium, in which 

 the germ lies rolled up. 



1315. Umbilicus and micropyle are united with each 

 other by means of seed or leaf-rib (raphe). Both rarely 

 stand opposite to each other, so as that the one should be 

 below, the other above ; but the apex of the leaf is 

 usually so involuted that it again reaches the bottom of 

 the leaf, whereby umbilicus and micropyle come into 

 close and mutual approximation, as in the beans. The 

 seed-petiole elongates itself into the seed-rib ; this is con- 

 tinued upon the back of the phyllodium or testa, bends 

 round, and returns again to the umbilicus, so as to de- 

 scribe a complete circle. The shell of the seed has con- 

 sequently the form of the young fern or fern-capsule. 



1316. The radicle is the continuation of the seed-rib, 

 which is, however, dismembered itself, moves off, and 

 thereby causes the micropyle to be, or, properly 

 speaking, only renders it, free. The testa or seed-shell 

 is consequently a phyllodium thrown over the germ, but 

 the micropyle is the upper opening of the bud. 



1317. The germ of the seed or embryo, namely, radi- 

 cle, cotyledons and plumule, is therefore only the quinary 

 pinnate leaf without the spathe or testa. 



1318. Thus the whole seed, shell and embryo, com- 



