STUDIES OX THE GEXETICS OF Ff^OWEB-COLOUKS, EVC. Vl'} 



15eiliaps beloiig to this categoiy, though the behaviour of the Froraugfi iu i^j 

 WHS uot yet examiuecl ; so will be parhaps also No. 13, where however uo seed 

 of white came to germinatiou. — Tlio procluctiou of some reels finm liomozygous 

 orauges, as seen iu Nos. 1, 2 (F,), 10, aud 25 is also explaiuixble by assumiug 

 the reversiou of oue allelomoiph, viz. the foruiatiou of some gametes CJRh 

 beside? ui irmal Crb, aud the occuiTeuce of the tertilisatiou CUb x C'i'h or 

 t'lib X Clib (or their reciprocal), giviug rise to red zygotes of the compasi- 

 tiou CCRrbb or C'CIilibb. — ^The productiou of magentas from wliites, as 

 seeu iu Xos. 21 aud 22 might also be duo to the revei-sioual chauge of oue 

 siugle allelomoi-ph ; siuce the J?\-whites iu these two Nos. are derived froai 

 the cross white-II X magenta, aud cousequeutly should possess the geuotypic 

 comiX)sitiou ccHRBB its uormal gametes are cUB, aud thus the forma- 

 tion of few gametes CRB bj- means of the reversion of C into C, aud the 

 mating of the latter, either -süth uormal gametes cRB or the mutated CRB 

 themselves will give rise to magenta zygotes, hetero- in the fii-st and horüuzygoivs 

 iu th9 second case. — In No. 2 (2^) we see the production of magenta fi'om 

 red, aud this is also evidently a simple process consisting iu the reversion of 

 one b into B, the development of iew gametes CRB as the consequence, 

 and the fei-tihsation CRB x CRb or its reciprocal. 



In the production of iuagentas fi'om orauges, as seen in Nos. 1 and 9, as 

 well as that of reds from wliites, as seen in No. 4, the occiureuce of a 

 simultaneous revei-sion of two allelomoiphs should be necessarily assumed. 

 Tluis iu the fii-st of two cases just cited the orange of the composition CCrrbb 

 must produce the gametes Ct'b (uormal) and CRB (mutated), aud iu the 

 sec-ond the white ccrrbb, the gametes crb (uormal) aud CRb (muLated)' 



The revei-sion process iu No. 27 ma^- be explained as follows : — the 

 orauge parent is here heterozygous, i.e. of the composition Ccrrbb ; since 

 normally the gametes Crb and crb (either male or female) are producefl iu 

 equal numbers theii- meetiug will give rise to 3 orauges : 1 wliite, so that if 

 magentas aud reds segi-egated out iu this case are considered to l)e orauges 



' The fonn.ation of the gametes of two kinil-s, viz. (JRh nnd Ct'B in the first case, anil 

 that of Crb anil cRb in the second will le.iil to the same results, but then the fertilisation 

 betn'een the two mutated gametes, viz. CRb x Cl'Ii as well .-is Crb x cTtb (or their reciprocal) 

 must be assum«! to ha.\c occuKled. 



