SCIENTIFIC COMMITTEE, MARCH 24. 



xxxiii 



Calanthes 1 Sibyl ' and ' Oakwood Ruby ' are very valuable and interesting, 

 and show still more clearly the application of the Mendelian principles to 

 Orchid hybrids. The fundamental principles of Mendel are three, viz. — 

 (1) the purity of the Dominants (D), (2) the purity of the Recessives (R), 

 and (3) the impurity of the DR's. In the case of the Calanthe hybrids 

 in question, according to Mr. Chapman's own facts, each of these three 

 principles is illustrated, viz. — (1) "In the bulb (of C. x 'Oakwood 

 Ruby ') the shape and general structure resembles C. rosea," i.e. a pure 

 Dominant. (2) The flowers of C x ' Sibyl ' are pure white, i.e. a 

 pure Becessive. (3) The flowers of C. x ' Oakwood Ruby ' are " dark 

 coloured," having been gradually intensified by selection of the darkest 

 forms (DR's) through four or five generations, i.e. impure DB's. 



With regard to the hybrids C. x VcitcJiii and Paphiopedilum x Leeanum, 

 which Mr. Chapman says he has raised true from seed, and which he 

 believes are therefore exceptions to "Mendel's Laws," allow me to assure 

 him that such well-known cases are not at all inconsistent with the 

 Mendelian principles. As I showed in the Journ. R.H.S. (1902), 

 xxvi. pp. 688-695, the hybrid P. x Leeanum in each single character 

 varies between its parents P. insigne and P. Spicerianum in every 

 degree of blending, presenting a perfect series of forms. 



So that if A represents P. insigne and B represents P. Spicerianum 

 the apparent result in P. x Leeanum is 1A + 2AB + 1B. 



According to Mendel's principles, if P. x Leeanum be self-fertilised 

 the actual result is apparently the same, viz. 1A + 2AB+ IB. 



So that one can quite understand Mr. Chapman's self-fertilised 

 hybrids coming apparently true from seed. 



The real difference between P. x Leeanum and its own offspring is, of 

 course, that, according to the Mendelian principles, in the latter case the 

 A's and B's would breed pure in the next generation, while in the former 

 case the A's and B's would breed impure AB's, though on the surface 

 both would appear to be the same. 



Many other interesting problems are suggested by Mr. Chapman's 

 facts; e.g. it seems possible that the weak constitution of C.x 'Oak- 

 wood Ruby' might be due to the correlated "bulb structure" being a 

 pure Dominant, i.e. C. rosea (a well-known miffy subject) rather than to 

 the intrinsic effects of inbreeding, as suggested by Mr. Chapman. But 

 space will not allow these matters to be followed up here, and I propose, 

 with Mr. Chapman's kind assistance in the way of material, to examine 

 these Calanthe hybrids in detail when they flower again, and report 

 the result in the Journal of the Society. 



To this Mr. Chapman replied : — 



" I am unable to follow Mr. C. C. Hurst in the matter of Dominant and 

 Recessive, characteristics in respect to the Calanthe hybrids. The colour in 

 Calanthe 1 Oakwood Ruby ' should, I think, be a pure Dominant. When we 

 consider that C. (Limatodes) rosea was rose to rose-carmine, and that the 

 dominating characters of the rose and rose-carmine have been intensified 

 in future generations, I am unable to discern where the recessive 

 characteristics apply. That the colour of Calanthe ' Oakwcod Ruby ' is 

 Dominant and of a fixed nature is shown in the only cross that has yet 

 flowered from its influence, viz. Phaio- Calanthe 1 Ruby.' 



B B 



