174 Elementary Biology. 



lies an actively growing mass of cells, the future stem, and 

 a body known as the hypocotyledonary axis, the tip- of 

 which is covered by the terminal cell of the suspensor. 

 This suspensorial cell divides transversely into two cells, the 

 cell next the embryo (the hypophysis) giving origin by 

 subdivision to a number of layers, the distal forming the 

 terminal portion of the root, while the proximal cells form 

 the embryonic root-cap, or calyptrogen. 



The embryology of the monocotyledon does not differ 

 from that just described, save that only one cotyledon is 

 formed, consequently the young stem seems to spring from 

 the side of the cotyledon rather than from the terminal part 

 of the embryo. The manner of arrangement of the cells of 

 the embryo is also somewhat different 



While these various changes have been taking place in 

 the interior of the ovospore, concomitant changes have been 

 occurring in the surrounding tissues of the ovule and ovary. 

 After fertilisation the ovule becomes the seed, and the 

 ovary, with its contained seed, the fruit. The outer covering 

 of the ovule (now of the seed), is termed the testa, the inner 

 the tegmen. Similarly, the ovarial wall, when it forms the 

 wall of the fruit, receives the name of the pericarp, not in- 

 frequently differentiated into three layers, the epi- meso- and 

 endo-caip. In some fruits the floral axis swells up round 

 the ovary, and, becoming succulent, forms what is known as 

 a false fruit, or pseudocarp. This does net, however, take 

 place in the type which we are considering. 



We have already seen how the various tissues of the 

 adult plant are differentiated from meristem. The plant so 

 formed may, like the lily, live only one year ; it is then 

 termed an annual, and its individual life, as a rule, ceases 

 after it has matured its fruit. Plants which thus flower only 

 once are termed monocarpic ; others, again, flower after 

 they are two years old and then die (biennial monocarpic) ; 

 others only after they have lived for a number of years 

 (perennial monocarpic). The majority (especially of dico- 



