166 A Defence of Menders 



would seem to indicate that the white round and the blue 

 wrinkled peas are distinct varieties derived from ancestors 

 respectively possessing one only of those marked qualities ; and, 

 in my opinion, the white round peas trace their origin to a 

 dwarfish pea having white flowers and round white seeds, and 

 the blue wrinkled varieties to a tall variety, having also white 

 flowers but blue wrinkled seeds. It is also noticeable, that from 

 a single cross between two different peas many hundreds of 

 varieties, not only like one or both parents and intermediate, 

 but apparently differing from either, may be produced in the 



statements are not mutually consistent. We have dominance of 

 round white in first cross. 



In the second generation blue wrinkled give only blue wrinkled, 

 and blue round give blue wrinkled and round, in accordance with 

 general experience. But we are told that white round give only 

 white round. This would be true of some white rounds, but not, 

 according to general experience, of all. Lastly we are told white 

 wrinkled give all four classes. If we had not been just told by 

 Laxton that the first cross showed dominance of white round, and 

 that blue wrinkled and blue round give the Mendelian result, I should 

 hesitate in face of this positive statement, but as it is inconsistent with 

 the rest of the story I think it is unquestionably an error of statement. 

 The context, and the argument based on the maple crosses show 

 clearly also what was in Laxton's mind. He plainly expected the 

 characters of the original pure varieties to separate out according to 

 their original combinations, and this expectation confused his 

 memory and general impressions. This, at least, until any such 

 result is got by a fresh observer, using strict methods, is the only 

 acceptable account. 



Of the same nature is the statement given by the late Mr Masters 

 to Darwin (Animals and Plants, i. p. 318) that blue round, white round, 

 blue wrinkled, and white wrinkled, all reproduced all four sorts during 

 successive years. Seeing that one sort would give all four, and two 

 would give two kinds, without special counting such an impression 

 might easily be produced. There are the further difficulties due to 

 seed-coat colour, and the fact that the distinction between round and 

 wrinkled may need some discrimination. The sorts are not named, 

 and the case cannot be further tested. 



