HESULTS WITH HYBRIDIZATION 



109 



Fig. 32. — The effect of three degrees of relationship in crossing is here 

 illustrated. Nos. 3 and 4 are pure strains inbred for three years. No. 

 2 from a close fertilized seed-stock, the plants each year fertilized from 

 sister plants from the same ear. No. 1 is from a seed-stock, cross fer- 

 tihzed for three years. 



PURE STRAINS, OR BIOTYPES 



80. Doctor Shull first presented the idea that a corn- 

 field is to be considered more or less a mixture of pure types 

 (biotypes) and that most of the plants in a field are more 

 or less complex hybrids. By inbreeding, some of the 

 original pure types might be isolated. In other words, a 

 cornfield is a complex mixture of types, and inbreeding 

 gives much the same result as does a chemical analysis with 

 a complex compound — resolves it into its original elements. 



