204 FIELD CROPS FOR THE COTTON-BELT 



250. Degrees of relationship among corn plants. It 

 is possible to have several degrees of relationship among 

 corn plants. These may be summarized as follows: 



1. Inbreeding, occurring when the pollen from a plant 

 fertilizes the ovules of the same plant. 



2. Close breeding, occurring when the pollen of a plant 

 fertilizes the ovules of a sister plant, or those of a plant 

 that has grown from the kernels of the same ear. 



3. Narrow breeding, occurring when pollen from a plant 

 fertilizes the ovules of a plant not closely related but of the 

 same variety. 



4. Broad breeding, occurring when the pollen from a 

 plant fertilizes the ovules of a plant of a different variety, 

 or occurring when the pollen from a plant fertilizes the 

 ovules of a plant of a different group, as between dent and 

 flint corn. 



251. The transmission of characters Mendel's 

 law. Inheritance in plants may be studied by two 

 methods: (1) by the statistical method of considering 

 plants and their offspring collectively; (2) by the analytical 

 method of studying the separate characters and their 

 modes of transmission. The present conception of plants is 

 that they are composed of separately heritable units known 

 as " unit-characters." Examples of such unit-characters 

 in corn are: the color of the grain, cob, stem or husks; the 

 character of the endosperm; the height of the plant; sus- 

 ceptibility or immunity to disease, and the like. The law 

 governing the transmission of such unit-characters from 

 parent to offspring was first discovered by Gregor Mendel, 

 an Austrian monk, in 1865, and rediscovered by de Vries 

 and others in 1900, and is now known as " Mendel's law 

 of hybrids." The manner in which the splitting up and 

 redistribution of parental characters occurs in hybrids 



