158 THE ORCHID REVIEW. [May, 1903. 
MENDEL’S PRINCIPLES AND ORCHID HYBRIDS. 
AT the meeting of the Scientific Committee, held on March 24th, the fol- 
lowing communication from Captain C. C. Hurst, F.L.S., was read :—The | 
additional facts, presented by Mr. Chapman at the last meeting, respecting — 
the hybrid Calanthes ‘‘ 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 D.R’S. In the case of the 
Calanthe hybrids in question, according to Mr. Chapman’s own facts, each 
of these three Mendelian principles is illustrated, viz.:—(1) In the bulb 
(of C. x ‘Oakwood Ruby”) the shape and general structure resembles C. 
rosea, t.¢., a pure Dominant; (2) /The flowers of C. x ‘‘ Sybil” are pure 
white, i.c., a pure Recessive; (3) The flowers of C. x ‘“‘ Oakwood Ruby” 
re “‘ dark coloured,” having been gradually intensified by selection of the 
darkest forms (D.R.’s) through four or five generations, i.e.-impure D.R.’s.. 
With regard to the hybrids C. x Veitchii 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 Men- 
delian Principles. As I showed in Journ. Roy. Hort. Soc., xxvi, 1902, 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, form- 
ing a perfect serié$ of forms. So that if A represents P. insigne, and B 
represents P. Spicerianum, the apparent result in P. x Leeanum is 1 A + 2 
AB-+ 1B. According to Mendel’s Principles, if P. x Leeanum is self- 
fertilised the actual result is apparently the same, viz.:—r1 A+2AB+4+1 
B. 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 
A B’s, though on the surface both would appear to be the same. 
~Many other interesting problems are suggested by Mr. Chapman's 
facts. It seems possible that the weak constitution of C. x ‘* Oakwood 
Ruby” might ke 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 results. 
