HYBRIDIZING PLANTS 123 



realized the vast possibilities for the improvement of plants 

 and have employed thousands of people in the work. 

 "Hunger Fighters" by De Kruif gives a few examples of the 

 results. Only a few examples are given in the next chapter, 

 but gardeners have used the method to develop thousands 

 of new plants. Common examples are the hundreds of varie- 

 ties of roses, irises, tulips, peas, while the number of varieties 

 of the staple grains such as wheat, barley, corn, sorghum, and 

 rice can be counted in the tens of thousands. 



It is impossible for most individuals to become acquainted 

 with all of the vast amount of work that has been done, but 

 before the actual work of hybridizing is begun, it is wise to 

 get a knowledge of cell structure and the principles and laws 

 which have been found to be fundamental. More failures 

 than successes will result and the beginner must plan to do 

 years of work if he hopes to attain the satisfaction of a plant 

 breeder. But for the amateur there is no greater thrill than 

 the creation of a new and distinctive variety. These new 

 varieties can often be entered in competition in flower shows 

 and recognition by the judges brings the satisfaction of real 

 creative achievement. 



In some respects plant breeding is as much an art as a 

 science, but the inheritance of characters is based on certain 

 principles and laws which must be understood by the plant 

 breeder. The fundamental principles of development are: 

 first, all organisms develop from a single cell by a long series 

 of cell divisions; second, since these divisions separate the 

 chromosomes equally all cells of the organism bear the same 

 assortment of genes, and third, each gene can be considered 

 as a minute portion of a chromosome located at a definite 

 place in the chromosome and determining the expression of 

 one or more characters of the organism in the course of 

 development. The fundamental laws of inheritance were 

 discovered by Gregor Johann Mendel and will be explained 

 shortly. 



The laws of inheritance, now called Mendelian laws, are 



