44 FIELD 'CROPS 



of varieties. If seed is continually saved from the best indi- 

 viduals in a field of wheat or other close-fertilized plant, a 

 very noticeable improvement can be effected in a few years. 

 In the same way, if the best individuals of open-fertilized 

 plants are saved for seed, improvement will result, but care 

 must be taken to prevent the introduction of pollen from 

 inferior plants. Thus an ear of corn may appear to be 

 excellent, but some of the kernels may have been fertilized 

 by pollen from inferior stalks and the plants they produce 

 will be inferior. A large part of this "bad blood" may be 

 eliminated by going through the field when the plants are 

 in tassel but before the pollen is shed and pulling out the 

 tassels of the weak stalks and others that do not show 

 promise of producing good ears. The improvement of 

 plants is a very interesting line of work and one which 

 should receive the attention of many more people than now 

 devote their energies to it. 



LABORATORY EXERCISES 



1. Soak several beans or peas in tepid water for 24 hours. Then 

 examine them, noting how they have swelled and how easily the outer 

 skin may be removed. Separate the halves and examine the embryo 

 which remains attached to one of them. At the same time put a few 

 beans in ice water and keep the water below 40 degrees if possible, 

 but avoid actual freezing. Note how little the seeds have swelled 

 in comparison with the others. Also soak a few beans for the same 

 length of time in tepid water containing a spoonful of common salt. 

 Note that they have not swelled as did those in warm water. Seeds have 

 the power of keeping out undesirable solutions and will not germinate 

 in soils containing any considerable quantity of salts. 



2. Plant several beans in a small box of good soil; plant kernels 

 of corn in a similar box. Keep the soil moist, but not wet. In a few 

 days the plants will appear. Note how the young shoot of the bean 

 has pushed the halves of the seed apart and forced them to the surface, 

 while the kernel of corn remained below. Dig up one plant of each 



