STUDIES ON THE GENETICS OF FLOWER-COLOURS, ETC. 
105 
From Table IV as well as what I have just stated we will see that we 
have here apparently to deal with a typical case of diliybrid segregation. 
In the various cases studied till now by several authors it was found 
that for the production of bluish-red colour (magenta, purple, etc.) the factor 
for producing the red anthocyanin and that for changing the latter into 
bluish-red one participate ; thus, for instance, in flowers of Lathyrus odoratus 
(jR and JB, Bateson)', and of Antirrhinum majus (F, It, D, Baue ; 2 II or L, 
T and li, Miss Wheldale), 3 in the aleurone of Maize (It and P, East and 
H ayes ; 4 It and Pr, Emerson), 5 etc. The question naturally arises whether 
the magenta colour of flowers of Portulaca is not also due to the combined 
action of such factors. The results of our present cross do furnish, as will be 
seen from what was stated above, no positive evidence towards such a 
conclusion, but some other breeding experiments, especially the Cross VIII 
(p. 112), prove beyond all doubts that the magenta colour in our case is 
due, quite similarly as in all cases above cited, to the action of the two 
factors which I call It (reddening) and I* (blueing) respectively. We have 
therefore in the hybrid white-I x magenta or its reciprocal a trihybrid instead 
of a dihybrid, inasmuch as it may be expressed by the genetical formula 
CcJEtrJBb, as above given. If the three factors C, It, B contained in this 
hybrid will make free assortment, we should have eight kinds of male and 
female gametes, i.e. CItP, cJEtB, CrP, crP, Cltb, cltb, Crb, crb, and 
consequently the ratio of 27 magentas : 9 reds : 12 oranges : 16 whites in FA The 
reason why notwithstanding this we have in our case the ratio of 9 magentas : 
3 oranges : 4 whites in F, will be seen, when we think that of the three 
factors C, It, I> contained in magenta the two latter are in the state of 
complete “ coup lin g ” or “ linkage ” (to use the word more frequently adopted 
recently), and act just like one single factor, so that we have here simply 
four kinds of male and female gametes, i.e. CltB, cRB, Crb, crb. If It 
1 Mendel’s Principles of Heredity, p. 91. 
2 Zeitsch. f. ind. Abstamm, u. Vererbungs’ehre, Bd. 3, 1910, pp. 41-43. 
3 Ibid., p. 326 ; also Journ. of Genetics, Vol. 4, 1915, p. 110. 
4 Conn. Agric. Exp. Stat., Bull. No. 167, 1911. 
5 Cornell Univ. Agric. Exp. Stat.,Memoirs 16, 1918. 
6 This is somewhat similar to the F.. -generation of the classical example of Sweet Pea (s. 
Bateson, 1. c., p. 91), though we have in the latter 28- whites instead of 12 oranges and 16 
whites, since the factor C does not produce any colour in Sweet Pea. 
