166 On the Reproductive Functional [No. 3, 



the proportions are as '23 to *29, relatively to the pure unions 

 of the latter. Thus, in whatever way we proceed, the general 

 results are the same, testifying to the highly remarkable fact 

 announced by Gartner, that varieties of a species, characterised by 

 no other differences than that of colour, are occasionally so differen- 

 tiated functionally, that the cross-unions, as compared with the 

 fertility of the pure unions, invariably indicate a certain degree of 

 sterilisation ! 



In connection with this higher relative fertility of homochromatie 

 to that of heterochromatic unions, as limited to the crossing of varieties 

 of a single species, I will venture to add that this law not only holds, 

 but, as I believe, extends to and regulates the functional relations in 

 accordance with the relative colour affinities of the varieties crossed. 

 Thus for the sake of illustration, we may take the three primary 

 colours of the cyanic series, namely, blue, violet, and red. Now 

 beginning with red, we know that greater physiological changes 

 must take place in the minute anatomy of the petals of an origi- 

 nally red-coloured flower to give the impression of blue than 

 that of violet. Hence we might suspect that a species presenting 

 varieties characterised by such differences in colour, would like- 

 wise afford different degrees of fertility in their conjunctive func- 

 tional relations, the blue and red yielding less fertile unions, 

 than the violet and red ; while the violet holding an intermediate 

 colour position between these, might be equally as fertile in its unions 

 with the blue as the red variety. In practical illustration of these re- 

 lations, we may take the results of the various unions of V. pliceniceum 

 and varieties given in Table 1. Thus the V. pliceniceum with pur- 

 plish-violet flowers yields more seeds when fertilised by the pollen 

 of the rose-coloured variety, than by that of the white variety, in the 

 proportion of 5 to 4. Again the white variety of V. pliceniceum 

 fertilised by the pollen of the rose variety yields an average of 29 

 seeds per capsule, and by that of the purplish violet variety the 

 average per capsule is 26, that is as 9 to 8, in favour of the unions 

 of the rose and white varieties. "We see here evident co-relations be- 

 tween the degrees of fertility and the colour affinities of these plants in 

 their respective sexual unions, and I venture to look for more marked 

 differences in these respects, had we as subjects of experiment, 



