154 A Defence of Mendel's 



Weldon, stating they may be considered separately, writes 

 as follows : 



"Tschermak has crossed Graue Riesen with five races of 

 P. sativum, and he finds that the form of the first hybrid seeds 

 follows the female parent, so that if races of P. sativum with 

 round smooth seeds be crossed with Graue Riesen (which has 

 flattened, feebly wrinkled seeds) the hybrids will be round and 

 smooth or flattened and wrinkled, as the P. sativum or the 

 Graue Riesen is used as female parent*. There is here a more 

 complex phenomenon than at first sight appears ; because if the 

 flowers of the first hybrid generation are self-fertilised, the 

 resulting seeds of. the second generation invariably resemble 

 those of the Graue Riesen in shape, although in colour they 

 follow Mendel's law of segregation!" 



From this account who would not infer that we have 

 here some mystery which does not accord with the 

 Mendelian principles ? As a matter of fact the case is 

 dominance in a perfectly obvious if distinct form. 



Graue Riesen, a large grey sugar-pea, the pois sans 

 parchemin geant of the French seedsmen, has full-yellow 

 cotyledons and a highly coloured seed-coat of varying tints. 

 In shape the seed is somewhat flattened with irregular 

 slight indentations, lightly wrinkled if the term be preferred. 

 Tschermak speaks of it in his first paper as " Same flack, 

 zu-sammengedruckt' -a flat, compressed seed ; in his second 

 paper as "flciche, oft schwach genmzelte Cotyledonen-form" 

 or cotyledon-shape, flat, often feebly wrinkled, as Professor 

 Weldon translates. 



First-crosses made from this variety, each with a differ- 

 ent form of P, sativum, are stated on the authority of 

 Tschermak's five cases, to follow exclusively the maternal 

 seed-shape. From "schwach gerunzelte," "feebly wrinkled," 

 Professor Weldon easily passes to " wrinkled," and tells us 



* Correns found a similar result. 



