INFLORESCENCE AND FLOWERS FIIUIT AND SEED 135 



tissue, across which minute vascular bundles run from 

 the embryo into the cotyledons. If the shell-like invest- 

 ments described above are removed from the embryo, it 

 is then possible to gently separate the cotyledons and 

 see the minute plumule and radicle to which they are 

 joined (fig. 36) ; on removing one cotyledon the plumule 

 will be seen embedded in a slight depression at the base. 

 At this point there is a little room to spare, not quite 

 filled up by the radicle and plumule; a minute remnant 

 of endosperm may occasionally be found here, not having 

 been entirely absorbed by the developing embryo. 



The cotyledons and embryo are composed of a 

 delicate epidermis enclosing the whole (fig. 37, e), and 

 very thin-walled cells forming the main mass of tissue 

 in which the vascular bundles run. These bundles are 

 scattered in the thickness of the cotyledons, ready to 

 convey fluids to and fro on germination, and already 

 contain lignified vessels in the xylem and sieve-tubes in 

 the phloem. 



The iso-diametric, closely-packed cells of the cotyle- 

 dons are filled with reserve materials, consisting of 

 large quantities of starch grains embedded in proteids 

 and tannin. Here and there are scattered cells filled 

 with brown pigments and containing tannin; some 

 cells also contain oil-drops. Traces of sugar (quercite), 

 certain bitter principles, acids, and mineral substances 

 also occur in the tissues. 



