ORCHID CONFERENCE. 



427 



primary hybrid back to one of its parents cannot be expected to succeed, 

 because suCh a mating implies the presence of a single' dose only of one 

 of the two characters concerned. By such a mating one of the char- 

 acters is secured by a double dose at the expense of the other, which can 

 only have a single dose. • Further, the many attempts that have been 

 made to secure the result by breeding from secondary and more com- 

 plex hybrids only lead to unnecessary complications, because owing 

 to segregation it is quite possible to lose the desired factor altogether 

 in the second generation Pg, and the securing of a double dose of it by 

 means of such matings is a matter of considerable uncertainty, with the 

 chances very much against the breeder. 



In passing, it may perhaps be useful to point out that the common 

 practice of analysing Orchid hybrids of complex parentage in terms of 

 fractions of their parents and ancestors is to be deprecated. In Orchid 

 literature we often see it stated, for instance, that a certain hybrid is 

 made up of Ja, Jb, Jc, and -|d. In the modern light of Genetics such 

 statementis are not only misleading, but in most cases they must of 

 necessity be erroneous. The simple fact of the segregation of char- 

 acters in the second generation altogether upsets such a calculation. 

 It is the pedigree that may be said to be so constituted, not the 

 individual hybrid. 



So far, we have dealt with the three particular problems by ap^jly- 

 ing the principles of Genetics in a general way to enable the breeder 

 to secure a definite result in the shortest possible time. Space will not 

 allow one to deal with the interesting mass of minor details concerned 

 in these three problems. One or two special points however may be 

 noted. Judging from the F-, results recently produced it would appear 

 that in order to get a true scarlet crispum, Cochlioda Noezliana should 

 be crossed with an Odontoglossum with a white ground colour — ■ 

 e.g., 0. crispum. or 0. Pescatorei; and in order to avoid, if possible, the 

 presence of purple sap in the segments it would seem advisable to use 

 the albino 0. crispum xanihotes or 0. Pescatorei album in preference 

 to the tinged, blotched, or plain forms, using, if possible, Charles- 

 worth's individual E forms of these albinos, which breed true when 

 crossed. 



In order to get a crimson crispum it would appear that Cochlioda 

 Noezliana should be crossed with an Odontoglossum with a yellow 

 ground — e.g., 0. triumphans or 0. luteopurpureum ; and to avoid the 

 dull purple tint in the crimson, the xanthic albinos 0. triumphans 

 ' Ajax ' and 0. luteopurpureum Vuylstekeanum might perhaps be used 

 to advantage. The presence of some purple sap in the column of 

 Cochlioda Noezliana may or may not complicate matters. It all depends 

 whether the column colour is inherited independently of the rest of the 

 flower or not; if a form can be secured in which the usual purple 

 colour in the column is absent, this possible complication might be 

 avoided. 



In the making of a scarlet Oattleya the elimination of the rose- 

 purple sap of the Oattleya is equally important in order to get the true 



