R. K. Nabours 43 



The essential difference between this conception and those prevailing 

 in most of the literature and practically all text books on the subject 

 is that two factors, P and S, which are paired, each with the other, and 

 one factor, <l>, which is not paired, unless it be with its absence, are 

 considered. Rose is a modified single and in no sense a character. 

 Walnut is a modification by the factor <I> of pea and the combination of 

 pea and single. 



The same consideration may be given to the crossings of round 

 yellow with wrinkled green peas. Having in mind the behaviour of @ 

 and any two multiple allelomorphs in ParateUix, it appears that Mendel's 

 experiment, (2), pp. 333, 334, consisted of one pair of factors, round and 

 wrinkled, each allelomorphic to the other, and a factor for yellow which 

 is allelomorphic only to its absence as © in Paratettix and <i> in combs 

 of fowls. Allowing R to represent the factor for round and W the 

 factor for wrinkled, the two making an allelomorphic pair, and A the 

 unpaired factor for yellow, we have a case of crossing RARA x WW, 

 with the product in Fi,R WA. These inbred produced in F2, considering 

 only those tested by Mendel, 



Green is common to the albumen of peas. It may be that peas are 

 all homozygous for the factor, or factors, causing green, but the green 

 does not pair, as an allelomorph, with yellow. It does not matter, in 

 this consideration, whether the factor for yellow causes yellowness in 

 addition to, and to the obscurity of, gTeen, or whether it inhibits or 

 destroys something to prevent the green from showing. 



It may be remarked, in this connection, that if all fourteen Paratettix 

 multiple allelomorphs, so far discovered, should be made homozygous 

 for ©, which could be easily accomplished, and all of them segregated, 

 there would be no chance of securing pure multiple allelomorphs again 

 from this group. As a matter of fact the forms with the double doses 

 of ^ would themselves become multiple allelomorphs. This may be 

 true now with respect to certain characters in Paratettix, e.g., the 

 triangular black spots on each side of the mid-pronotum which are 

 common to all forms. However, since all of them appear to have it 



