n6 



NATURE OF THE SEED 



pyle, exists in the integument. This opening is seen near the 

 scar or hilnm that marks the point where the seed was attached 

 by a minute stem to the walls of the ovary (Fig. 83, B). This 



FIG. 83. Fruit and seed of the bean: A, mature fruit or pod: s, style; 

 c, remains of calyx; o, ovary. At left the pod has been opened, showing 

 four seeds attached to the walls of the ovary by funiculus. B, two views 

 of a seed h, hilum or scar marking attachment of funiculus to seed; m, 

 micropyle. C, wrinkling of seed coat caused by the entrance of water 

 through the micropyle and hilum. D, embryo of seed after removal of 

 integument c, cotyledons. At left one of the cotyledons has been removed 

 to show the plumule, or epicotyl, ep, and the hypocotyl, hy. E, half of the 

 membranous integument. 



opening permits the entrance of the air and water as does the 

 looser structure of the hilum. This can easily be demonstrated 

 by placing beans in water when the spread of the water from the 

 region of the micropyle will be indicated by the swelling and 

 wrinkling of the integument (Fig. 83, C). After a time the 

 entire integument becomes quite soft and water is readily drawn 

 through it owing to the fact that the storage foods in the embryo 

 are in close contact with it and draw the water through by os- 

 mosis. Carefully removing the integument from a soaked bean 

 we note that the embryo is well developed, consisting of two 

 fleshy cotyledons and a short stem (Fig. 83, D, E). The epi- 

 cotyl is well developed forming a plumule bearing two leaves 

 and the short hypocotyl and root are enclosed in a sheath formed 

 from the integument. Note that the hypocotyl and root are 

 situated near the micropyle. How does this arrangement work 



