MENDEL'S "LAW" APPLIED TO ORCHID HYBRIDS. 



693 



Hybrid 



Parents 



Specifics 



" Inter- 



mediatc':s " 



P. X porphyrochlamys . 



P. X Quies 



P, X Richmanii 



P. X Rolfei . 



P. barbatum x P. hirsutissimum 



P. Curtisil X P, Hookera? 



P. barbatum x P. bellatuluiii . 



P. bellatulum x P. Rothschildianum 



4 

 42 

 16 



6 

 56 

 32 

 26 



6 

 10 

 14 



4 

 24 

 10 

 14 



8 

 22 



8 

 36 

 16 

 12 



4 

 38 

 20 



4 

 44 

 28 

 34 



4 



10 

 10 



6 

 16 



6 

 12 



6 

 18 



6 

 34 

 20 



4 



P. X selligerum 



P, X superciliare . 



P. X Swinbuinei 



P. X Tautzianum , 



P. X tessellatum 



P. X vexillarium 



P. X Vipani , 



P. X Winnianum . 



P. X Youngiae 



P. X Youngianum . 



Phragmipedilum x Cleola 



P. X Dominianum . 



P. X grande . 



P. X Sedenii . 



Sobralia x Veitchii 



^ygopetalum x Perrenoudi 



P, barbatum x P. philippinense 

 P. barbatum x P. superbiens . 

 P. Argus X P. insigne 



P. barbatum x P. niveum 

 P. barbatum x P. concolor 



P. barbatum x P. Fairrieanum 

 P. niveum x P. philippinense . 

 P. Druryi x P. villosum . '. 



P. bellatulum x P. Hookera? . 

 P. superbiens x P. philippinense 



P. Boissierianum x P. Schlimii 

 P. caricinum x P. caudatum . 

 P. caudatum x P. longifolium 

 P, longifolium x P. Schlimii , 

 S. macrantha x S. xantholeuca 

 Z. Gautieri x Z. intermedium 



Total 



2,281 



2,267 



The results of the analyses given above may be summarised as 

 follows : — 



Out of 4,548 pairs of specific characters united by hybridisation, 

 2,281 are classed as " specifics " and 2,267 as " intermediates." In other 

 words, we find that specific characters, taken singly, associate themselves 

 approximately in intermediate hybrids at the rate of one-half " specifics " 

 and one-half "intermediates." 



Now if A and a represent the " specifics " generally, and Aa the 

 "intermediates," we get the formula 1,141 + 2,267 Aa + 1140 a, 

 which, simplified, becomes approximately A + 2Aa + a. 



That the "specifics " together are made up on the average of equal 

 numbers of A and a the following instance will show : — 



Take, e.g., Paphiojpedilum x Leeanum. In this case a large number 

 of hybrids were analysed, giving in all 492 characters. Of these 248 

 were " specifics " and 244 were " intermediates." Of the 248 " specifics," 

 127 were P. Spicerianum and 121 P. insigne. 



Now if P. Spicerianum = A, and P. insigne = a, the precise formula 

 in this case works out as 127 A + 244 Aa + 121 a, which, considering 

 the small numbers used, is a close approximation to A + 2Aa + a. 



Thus we see that the above formula for the union of specific 

 characters in intermediate Orchid hybrids is practically the same as 

 Mendel's formula for the separation of characters in crosses with Peas. 



In the next paper I will endeavour to show that this formula of 

 Mendel, though useful as working formula for hybrids of a certain 

 ancestry, has its limitations ; and that Mendel's theory in explanation 

 of that formula cannot generally be maintained w4th Orchid hybrids. 



(Since the above was written, an iynportant payer on the subject, by 

 Prof. IF. F. B. Weldon, F.B.S., has appeared, whicJi deserves careful 



