DESCRIPTIVE BOTANY. PAIIT J. 



com, wheat, &c. ; or of a seed of an onion, lily, &c. 

 (fig. 25.). An albuminous mass () forms the main 



bulk of most of these seeds, and the embryo (/y) is 

 placed within it towards the centre, or on one side. 

 The embryo is not so distinctly developed in the seeds 

 of this class as in those of the last, and its several 

 parts cannot always be readily recognised before 

 germination has commenced. Its general character is 

 that of a cylindrical body, tapering more or less at the 

 extremities, from one of which protrudes the radicle, and 

 from the other arises a single, conical, and almost solid 

 cotyledon. This elongates, and is ultimately pierced 

 by a leaf, rolled into a conical form, and which was at 

 first completely invested by the cotyledon. 



('_'.) Organisation of the Stem. 



In Monocotyledones, there is no distinction between 

 pith, wood, and bark ; but their stems consist of a cy- 

 lindrical mass of cellular tissue, through which bundles 

 of vascular tissue are distributed in a scattered manner 

 ( fig. 26.). Every fresh 

 development of new mat- 

 ter is carried towards the 

 centre of the stem, and, as 

 the stem elongates, the 

 outer parts become more 

 and more solidified, whilst 

 the inner remain soft. 

 These stems possess no traces of medullary rays. The 



