Chap. II. HYBRID VEBBASOUMS. 75 



per capsule. So that out of the eight possible unions 

 between the two forms of these two species, six 

 were utterly barren, and two fairly fertile. We have 

 seen also the same sort of extraordinary irregularity in 

 the results of my twenty different crosses (Tables 

 14 to 18), between the two forms of the oxlip, prim- 

 rose, and cowslip. Mr. Scott remarks, with respect 

 to the results of his trials, that they are very surprising, 

 as they show us that " the sexual forms of a species 

 manifest in their respective powers for conjunction 

 with those of another species, physiological peculiari- 

 ties which might well entitle them, by the criterion of 

 fertility, to specific distinction." 



Finally, although P. veris and vulgaris, when crossed 

 legitimately,-and especially when their hybrid offspring 

 are crossed in this manner with both parent-species, 

 were decidedly more fertile, than when crossed in an 

 illegitimate manner, and although the legitimate cross 

 effected by Mr. Scott between P. auricula and hirsuia 

 was more fertile, in the ratio of 56 to 42, than the 

 illegitimate cross, nevertheless it is very doubtful, 

 from the extreme irregularity of the results in the 

 various other hybrid crosses made by Mr. Scott, whether 

 it can be predicted that two heterostyled species are 

 generally more fertile if crossed legitimately (i.e. when 

 opposite forms are united) than when crossed illegiti- 

 mately. 



Supplementary Note on some wild hyhrid Verhascums. 



In an early part of this chapter I remarked that few 

 other instances could be given of a hybrid spontane- 

 ously arising in such large numbers, and over so wide an 

 extent of country, as that of the common oxlip ; but per- 

 haps the number of well-ascertained cases of naturally 



