THE PHENOMENA OF REVERSION 33 1 



minants is sufificient to predominate over the ' asymmetrical ' 

 determinants. 



The experiments which have been made with respect to the 

 transmission of characters in such abnormally peloric flowers, 

 prove that this explanation must be correct in principle. Dar- 

 win crossed the peloric snapdragon (^Antirrhimnn viajus) 

 with its own pollen, and from the seeds thus obtained raised 

 sixteen plants, which ' were all as perfectly peloric as the parent 

 plant.'* We need not be surprised that the pelorism was 

 inherited, for the 'peloric' determinants were in the majority in 

 the parental germ-plasm on either side ; it may, however, have 

 been due to chance that all the sixteen plants which were reared 

 proved to be peloric. If a larger number of offspring had 

 been raised, some of them would certainly have produced 

 asymmetrical flowers, for the reducing division would in most 

 cases divide the ' peloric ' determinants unequally amongst the 

 two resulting cells, and consequently two germ-cells containing 

 no, or only a minority of, 'peloric' determinants might meet 

 together in fertilisation. Reversion to the ordinary form of the 

 flower must then occur. 



The result of Darwin's counter-experiment is particularly 

 interesting. The peloric snapdragon was crossed with the 

 common form, and ' two great beds of seedlings ' f raised, ' ?iot 

 one of which was peloric." And in ninety plants which were 

 carefully examined there was not a trace of pelorism, 'except 

 that in a few instances the minute rudiment of the fifth stamen, 

 which is always present, was more fully or even completely 

 developed.' Darwin attempted to explain this fact by the 

 assumption that in this case the common form of the flower 

 possessed a ' prepotent force of transmission ; ' but apart from 

 the fact that this statement is merely another formulation of an 

 observed fact, and can hardly be looked upon as a real expla- 

 nation, it does not hold in the case of Darwin's subsequent 

 experiments. For the plants obtained by crossing the common 

 snapdragon with the peloric form, ^ which perfectly resembled 

 the common snapdragon, were allowed to sow themselves ; and 

 out of a hundred and twenty-seven seedlings, eighty-eight 

 proved to be common snapdragons, two were in an intermediate 



* 'Animals and Plants,' &c., Vol. II., i888, p. 46. 

 t Loc. cit.. Vol. II., 1888, p. 46. 



