lxxviii 



ROYAL HORTICULTURAL SOCIETY. 



of sap issuing from between the calyx and the abortive pericarp, 

 which last, unlike all the others on the plant, took a pinkish tint. 



August 17, 1868. 



Referring to my letter of Saturday, the question, I incline to 

 think, should rather be put in this form : — 



Between species, though allied, averse, or not hitherto found to 

 unite by crossing, is it possible to effect such a crossing by persis- 

 tent inoculation from year to year between the same two plants, 

 on the supposition that some principle predisposing to such union 

 is ultimately communicated by the pollen of the male to the seed- 

 bearing plant ? 



Or, attending to the circumstances, the Committee may, if they 

 see necessary, improve the question. One test might be to re- 

 peat my experiment between Rhododendron Edgworthii and Azalea 

 stella, making, as I have done, the latter the seed-bearer ; for I 

 have never found or known the Rhododendron Edgivorthii to reci- 

 procate a cross, at least with the smaller species, or, indeed, with 

 any. The experiment may be tried with both long and short an- 

 thers. It is with the shortest pair of the Edgivorthii-sta,m.eTis, and 

 with them only, that have I succeeded; and by these I have this year 

 successfully fertilized four seed-pods, all now beautifully swelled 

 and ripening. I mean next year to repeat the experiment on a 

 plant of A. stella not before operated on, again making the trial 

 with long and short stamens. In place of here repeating my views 

 about these separate stamens, and the use I have made of the 

 short ones over a period of seventeen years, I respectfully refer to 

 p. 5 of the accompanying paper, forming my Presidential Address 

 to the Botanical Society here, on " pure hybridization." 



I may be allowed to observe, on the above cross, that as Azaleas 

 in general are repellent of crosses by Rhododendrons, but more 

 especially by the larger species, to which both the Edgworthii and 

 Bucklandii belong, it appears to me to illustrate and corroborate 

 my opinions on one of three views alluded to in the accompanying 

 paper, viz. (1) of sympathy, (2) of the efficacy of the short stamens 

 of a larger species in accomplishing a cross by their finer-grained 

 pollen on a smaller kindred species, or (3) of predisposition 

 effected by repeated inoculation whereby the parents have to 

 some extent become of one blood. 



I had some other suggestions to offer, but must now defer them 

 I observe that our friend Mr. Murray alluded, at one of the 



