Principles of Heredity 157 



7. Debarbieux fertilised l>y Serpette nain blanc (yellow 

 cotyledons ; wrinkled ; white skin ; dwarf) gave one pod 

 with six seeds, size and shape of Debarbieux, with slight 

 dimpling. 



8. Debarbieux by nain de Bretagne (very small ; yellow 

 cotyledons; very round) gave three pods, 12 seeds, all 

 yellow cotyledons, of which two pods had eight seeds iden- 

 tical in shape with Debarbieux, while the third had four 

 seeds like Debarbieux but more dimpled. The reciprocal 

 cross gave two seeds exactly like nain de Bretagne. 



But it may be objected that the shape of this large 

 grey pea is very peculiar* ; and that it maintains its type 

 remarkably when fertilised by many distinct varieties 

 though its pollen effects little or no change in them ; for, 

 so long as round varieties of sativum are used as mothers, 

 this is true as we have seen. But when once it is under- 

 stood that in Graue Riesen there is no question of wrinkling, 

 seeing that the variety behaves as a round variety, the 

 shape and especially the size of the seed must be treated 

 as a maternal property. 



Why the distinction between the shape of Graue 

 Riesen and that of ordinary round peas should be a matter 

 of maternal physiology we do not know. The question is 

 one for the botanical chemist. But there is evidently very 

 considerable regularity, the seeds borne by the cross-breds 

 exhibiting the form of the "grey' : pea, which is then a 

 dominant character as much as the seed-coat characters 



h It is certainly subject to considerable changes according to 

 conditions. Those ripened in my garden are without exception much 

 larger and flatter than Vilmorin's seeds (now two years old) from 

 which they grew. The colour of the coats is also much duller. These 

 changes are just what is to be expected from the English climate 

 taken with the fact that my sample of this variety was late sown. 



