142 Plant-Breeding 



failures. Petunia by Nicotiana affinis, eleven efforts : 

 eleven failures. Nicotiana affinis by petunia, six efforts : 

 six failures. General Grant tobacco by Nicotiana affinis, 

 eleven efforts : eight successes ; three failures. Nicotiana 

 affinis by General Grant tobacco, fifteen efforts : fifteen 

 failures. General Grant tobacco by General Grant 

 tobacco, one effort : one success. Nicotiana affinis by 

 Nicotiana affinis, three efforts : two successes ; one failure. 

 Tuberous begonia, five efforts : five successes. 



"Total, three hundred and twelve efforts: eighty-nine 

 successes, two hundred and twenty-three failures." l 



Graft-hybrids. It is well known that, when two varie- 

 ties or allied species are grafted together, each retains its 

 distinctive characters. But to this general, if not uni- 

 versal, rule there are on record several alleged exceptions, 

 in which either the cion is said to have partaken of the 

 qualities of the stock, the stock of the cion, or each to 

 have affected the other. Supposing any of these in- 

 fluences to have been exerted, the resulting product would 

 deserve to be called a graft-hybrid. 



It is clearly a matter of great interest to ascertain 

 whether such formation of hybrids by grafting is really 

 possible ; for, even if one example of such formation could 

 be unequivocably proved, it would show that sexual 

 and asexual reproduction are essentially identical. 



The case of Cytisus Adami (Figs. 41, 42). The cases of 

 alleged graft-hybridization are exceedingly few, considering 

 the enormous number of grafts that are made every year 

 by horticulturists and have been made for centuries. 



Of these cases, one of the most celebrated is that of 



1 Bailey, earlier editions. 



