35° 



THE POPULAR SCIENCE MONTHLY 



Fig. 7. At left " Havana " Parent, at right " Cuban " Parent of Cross 

 shown in Fig. 8. The " Havana " has short habit of growth, large leaves averaging 

 19 to 21 in number. The " Cuban " has tall habit of growth and averages 26 medium- 

 sized leaves. 



duction of a purple variety. When these two white varieties are crossed, 

 the purple variety results. The second generation, however, produces 

 seven whites to every nine purples. Such segregation into purples and 

 whites may not he desirahle; all purples may be wanted. This brings 

 us to a consideration of class B of the four classes of phenomena at- 

 tending hybridization, the production of desirable character combina- 

 tions in the first hybrid generation and their continuation by asexual 

 propagation. This class really includes several distinct types of oc- 

 currences. The purple sweet pea produced from the two whites will 

 serve as an illustration of the first type. In certain plants (not mean- 

 ing the sweet pea, however) it is as simple to reproduce by cuttings as 

 by seed. The cuttings are simply parts of the plant from which they 

 come and are identical with it in character. 2 If in a species of this 

 kind a desirable character is formed by the union of two or more 

 hereditary factors and one wishes to reproduce the character indefi- 

 nitely, asexual reproduction by cutting serves the purpose admirably. 



2 There are certain cases like variegation that are exceptions to this rule. 



