DICOTYLEDONS. 175 



oblong, slightly flattened so as to be oval in section, and 

 divided into two chambers. The style is very short and tipped 

 by a round, flattened stigma. 



The raceme continues to grow for a long time, forming new 

 flowers at the end, so that all stages of flowers and fruit may 

 often be found in the same inflorescence. 



The flowers are probably quite independent of insect aid in 

 pollination, as the stamens are so placed as to almost infalli- 

 bly shed their pollen upon the stigma. This fact, probably, 

 accounts for the inconspicuous character of the flowers. 



After fertilization is effected, and the outer floral leaves fall 

 off, the ovary rapidly enlarges, and becomes heart-shaped and 

 much flattened at right angles to the partition. When ripe, 

 each half falls away, leaving the seeds attached by delicate 

 stalks (f uniculi, sing, funiculus) to the edges of the membranous 

 partition. The seeds are small, oval bodies with a shining, 

 yellow-brown shell, and with a little dent at the end where 

 the stalk is attached. Carefully dividing the seed lengthwise, 

 or crushing it in water so as to remove the embryo, we find 

 it occupies the whole cavity of the seed, the young stalk (st.) 

 being bent down against the back of one of the cotyledons (/). 



A microscopic examination of a cross-section of the older root shows 

 that the central portion is made up of radiating Imes of thick-walled cells 

 (fibres) interspersed with lines of larger, round openings (vessels). There 

 is a ring of small cambium cells around this merging into the phloem, 

 which is composed of irregular cells, with pretty thick, but soft walls. 

 The ground tissue is composed of large, loose cells, which in the older 

 roots are often ruptured and partly dried up. The epidermis is usually 

 indistinguishable in the older roots. To understand the early structure 

 of the roots, the smallest rootlets obtainable should be selected. The 

 smallest are so transparent that the tips may be mounted whole in water, 

 and will show very satisfactorily the arrangement of the young tissues. 

 The tissues do not here arise from a single, apical cell, as we found in the 

 pteridophytes, but from a group of cells (the shaded cells in Fig. 94, B). 

 The end of the root, as in the fern, is covered with a root cap (r) com- 

 posed of successive layers of cells cut off from the growing point. The 

 rest of the root shows the same division of the tissues into the primary 



