PLANT BREEDING z$i 



There is another case of a different kind. Sometimes the hybrid 

 character is different from the character of the parents, even though 

 the exact parental characters are reproduced by segregation in succeed- 

 ing generations. The commercial carnation form is the result of cross- 

 ing the single carnation with the huge worthless doubles called 

 " busters." Eeproduced bj seed the commercial carnation throws both 

 singles and busters, showing that segregation of the parental characters 

 takes place; but as these plants are easily reproduced by cuttings, and 

 the cuttings are all of the commercial type, sexual reproduction is only 

 resorted to for the sake of producing new varieties. Another common 

 phenomenon attending lwbridization is sterility. Many very beautiful 

 flowers produce no seed at all. This is even an advantage in some cases, 

 because the plants flower more profusely than if they were spending 

 their energies in the production of seed. Here again, cuttings are re- 

 sorted to to reproduce the hybrid, or, as in the case of seedless oranges, 

 the cuttings are grafted into an older rootstock instead of being rooted. 



I stated at the beginning that there were two other classes of 

 hybridization phenomena, the production of fixed first-generation 

 hybrids and the production of blend hybrids. It is probable in the last 

 analysis that the true explanation of these cases is the same ; so we will 

 consider them together. It is believed by many that there are kinds of 

 inheritance other than Mendelian, that is, inheritance where no segrega- 

 tion occurs. Far be it from me to deny this; I simply state the fact 

 that there are no exact data extant proving other kinds of inheritance. 

 Such data may be found, but it is useless to speculate upon other laws 

 without such evidence. There are several cases in which either new 

 characters that breed true or blended characters that breed true 

 appear to have been formed, but they have not been studied with 

 sufficient care for an analysis of their mode of inheritance to be accurate 

 and final. It is in crosses between true species that hybrids have been 

 formed seemingly as constant and uniform as their parent species. Janc- 

 zewsky has produced several such hybrids. Perhaps the most famous, 

 however, are the blackberry-raspberry crosses first produced by the late 

 E. S. Carman, editor of the Rural New-Yorker and later by Luther Bur- 

 bank and others. Several hybrids having a commercial value have been 

 made in this genus (Rubus), and all of them reproduce approximately 

 true from seed. These are the facts and show what may sometimes be 

 expected by hybridizers when crossing true species ; but I wish to point 

 out that this does not necessarily mean that we are dealing with a new 

 mode of inheritance. Bramble species produce seedlings that are quite 

 variable and in which the variations are extremely difficult to describe; 

 there is, therefore, no exact information as to the relative variability of 

 the hybrid seedlings as compared to that of the two parents. It may be 

 said, then, that it is yet unknown whether there is partial segregation. 



