PHANEROGAMIA. 405 



Grasses, etc.), the food is stored in the endosperm, the cotyledons 

 are absorbent organs and, though still relatively large, are not 

 thick and fleshy. 



In a few Phanerograms (e.g. Utricularia, which never developes 

 any root, Ruppia rostellata, Wolffia arrldza) no primary root is 

 developed or even indicated. 



The extra- seminal development of the embryo may be briefly 

 described as follows : The first event is the elongation of the 

 hypocotyl, with the result that the radicle passes, through the 

 micro pyle, out of the seed into the soil, where it becomes firmly 

 attached. The other members then escape from the seed, the coat 

 of which becomes more or less split. In those cases in which the 

 growth of the hypocotyl is active, the cotyledons appear above the 

 surface of the soil, that is, they are e.pigean (e.g. Cucurbita, Ricinus, 

 Radish, Sunflower, Scarlet Runner, etc., most G-ymuosperms), either 

 leaving the seed-coat in the soil, or carrying it up to the surface. 

 In those cases in which the growth of the hypocotyl is compara- 

 tively slight, the cotyledons do not reach the surface of the sail, 

 that is, they are hypogcan (e.g. Vicia Faba, Pea, Grasses, etc.) : 

 here it is the epicotyl (plumule) which grows rapidly, and is the 

 first member to appear above ground. The part which first appears 

 above ground, whether it be hypocotyl, epicotyl, or cotyledon, 

 usually does so in the form of an arch, so that the apex is not 

 exposed to injury whilst the member is forcing its way up through 

 the soil. 



Epigean cotyledons become green in colour, and in many cases 

 (e.g. Sunflower, Radish) assume the appearance, and discharge the 

 functions, of foliage-leaves ; but they do not ever precisely resemble, 

 either in size or form, the true foliage-leaves of the plant to which 

 they belong. 



Vegetative Propagation is common among Phanerogams, by 

 means of bulbs (e.g. Lily, Onion, and many other Monocotyledons), 

 tubers (Potato), tuberous roots (Dahlia), etc. 



B. THE GAMETOPHYTE. As all Phanerogams are heterosporous, 

 the sexual generation is represented by two individuals, a male 

 and a female, developed respectively from the microspore and the 

 macrospore. 



The Male Prothallium is, in all cases, filamentous and relatively 

 small, consisting of but few cells. The first indication of its 

 development is the division of the nucleus of the microspore, which 

 may take place even before the microspore escapes from the micro- 



