STRUCTURE OF SEEDS 17 



discussed. With corn, the experiment has been tried many times, 

 of planting the large kernels from the middle portion in comparison 

 with the smaller seeds near the ends of the ear. Very little differ- 

 ence in results is secured, as both kinds of kernels from the same ear 

 have the same hereditary qualities. It appears also that large and 

 small kernels from the same plant of wheat carry the same qualities 

 and ability to produce. Seed grain is sometimes run through a set 

 of screens to separate the large seeds from the small. However, if 

 the seed grain is good, sound grain, it is doubtful if it will pay to 

 make such separation. This conclusion is based on experiments re- 

 ported by the Ohio, 2 Kansas, 3 and Nebraska 4 Experiment Stations. 



Shrunken Seeds. The removal of shrunken seeds may be bene- 

 ficial where the percentage is high, and the soil or climatic conditiens 

 unfavorable. However, when sufficient seed is sown, it is doubtful 

 even if the presence of more or less shrunken seed will have much 

 effect. When cereals are sown at customary rates, so many plants 

 come up, that weak or slow plants are crowded out during the early 

 stages of growth. As this natural selection is going on every year in 

 cereal crops, they maintain their natural vigor and productiveness 

 much better than crops planted far apart, as corn or potatoes, and 

 thus relieved from natural competition. 



Structure of Seeds. All students should have 3, knowledge of 

 the structure of seeds and the factors that influence growth. 



The Food of Seeds. The seed is a storehouse of food for young 

 plants. Seeds may be divided into two groups, according to the way 

 food is stored : 



1. Food stored in cotyledons, or first two leaves. 



2. Food stored in endosperm. 



Seeds of the first class can be known when they germinate in the 

 soil, because the seed divides into halves, which are firmly attached to 

 the young plant. In some cases, the two halves of the seed are 

 pushed above ground, becoming the first two leaves. The young 

 plant, however, draws its first food supply from these leaves. 



Seeds of the second class remain whole and below ground, as the 

 endosperm is only a storehouse of food. 



2 Ohio Bulletin 165. 

 8 Kansas Bulletins 59 and 74. 

 4 Nebraska Bulletin 104. 

 2 



