124 s. IKENO : 



All cases mentioned in the above Table (with some exceptions) may be 

 explained according to one of several ways disenssed below, either alone or 

 combiued.' 



1. Reversion during the Formation of Gametes — Nos. 1, 2, 3, 4, 5, 6, 7, 

 8, 9, 10, 12, 13, 21, 22, 25, 2G, 27, 28 and 30 in the above Table may be 

 included here. All of them are explainable when we will assume a certain 

 reversional change of allelomorjjhs in cells concerned in the formation of gametes, 

 either male or female. The question, in what s!;age of development such a 

 change will take jilace cannot be yet exactly answered, bnt its occmTence 

 might be perhaps sought in the raluciug chvision leading to theü* formation, 

 especiallj' in synapsis stage. In some cases the reversion of one single 

 allelomorph into its coiTespouding suffices to explain the phenomenon, l)ut in 

 otliei-s that of two or even thi'ee allelomoiphs must be assumed. 



To begin with the simplest case : the white of the constitution ccrrbb 

 produces normally the gametes crb ; suppose that the reverse mutation of the 

 allelomorph C into C takes place in some cells concerned in the reducing 

 division, then the gametes Cfh will be produced besides the normal ones ct'h. 

 Since the number of the mutated gametes is certainly very small as compared 

 to that of normal ones the gametes Cfh will meet in fertilisation most 

 commonly with ci'h, though A^ery exceptionally the meeting of the mutated 

 male and female gametes C>'& might occm- ; the resulting zygotes are phseno- 

 tyjiically the same in both cases, \{z. orange, but geuotypically different, viz. 

 Ccrrbb in the fet and CCrrbb in the. second case. The production of 

 oranges fi'om whites, as seen in Nos. 6 (K,), 7 (Fi), 12, and 13 may he due 

 to such a reverse mutation. For instance, in No. (3 one orange has been 

 derivetl in F^ fir>m the seed taken on a i^ white jJant, and that orange 

 was found to segi'egate in I^ into 3 oranges : 3 wliites, proving thus itself to 

 be f)f the constitution Ccrrbb, though here the actual numbere of the two 

 kinds of segregates in F^ do not very weU agree with the calculated (4-5 : 1"5), 

 evidently on account of the small number of individuals. No. 12 juighfc 



1 Wliat are given below ate, as abjve stated, mere trials to explain the apjiearancc of 

 unexjiecteil iudivjiluals, and would contain necessarily some defects and mistakes, es))ei;iidly as 

 the very i)Oor germination of seeds makes the explanation iliCficult. and in certain civses even 

 almost impossible. It would 1« (jnite possible that in future some of tUem might be replmred 

 by much better ones. 



