70 



BIOLOGY AND HUMAN LIFE 



successful in establishing themselves in a new territory than 

 plants with small seeds. We shall find, however, that the best 

 spreaders in the plant world are those with rather small seeds. 



Fig. 35. Young plants emerging from seeds 



On the left, squash; on the right, bean. In the squash a little outgrowth on the 



hypocotyl keeps the seed coat in place while the cotyledons are carried aloft. C, C, 



cotyledons; E, epicotyl; H, hypocotyl; gg, ground line 



The speedy and secure establishment of the individual plant is 

 of great advantage, but it is even more important that seeds 

 be well scattered, and in this respect the small-seed plants with 

 very numerous seeds have a decided advantage. 



LIVING CONDITIONS; THE SEED 



1. Nothing exists by itself 



Living things are dependent 



Upon non-living materials and conditions 

 Upon one another 



2. Seeds as showing dependence 



Dependence upon water Dependence upon temperature 



How demonstrated Maximum ; minimum ; optimum 



Amount of water needed Relation to air 



