Principles of Heredity 165 



I have also deduced from my experiments, in accordance 

 with the conclusions of the late Mr Knight and others, that the 

 colours of the envelopes of the seeds of peas immediately 

 resulting from a cross are never changed*. I find, however, 

 that the colour and probably the substance of the cotyledons 

 are sometimes, but not always, changed by the cross fertilisation 

 of two different varieties ; and I do not agree with Mr Knight 

 that the form and size of the seeds produced are unaltered t; 

 for I have on more than one occasion observed that the coty- 

 ledons in the seeds directly, resulting from a cross of a blue 

 wrinkled pea fertilised by the pollen of a white round variety 

 have been of a greenish-white colour |, and the seeds nearly 

 round and larger or smaller according as there may have been 

 a difference in the size of the seeds of the two varieties||. 



I have also noticed that a cross between a round white and 

 a blue wrinkled pea will in the third and fourth generations 

 (second and third years' produce) at times bring forth blue 

 round, blue wrinkled, white round and white wrinkled peas in 

 the same pods, that the white round seeds, when again sown, 

 will produce only white round seeds, that the white wrinkled 

 seeds will, up to the fourth or fifth generation, produce both 

 blue and white wrinkled and round peas, that the blue round 

 peas will produce blue wrinkled and round peas, but that the 

 blue wrinkled peas will bear only blue wrinkled seeds IF. This 



The nature of this mistake is now clear ; for as stated above 

 xenia is only likely to occur when the maternal seed-coat is pigmented. 

 The violet coats in this experiment are themselves cases of xenia. 



f Knight, it was seen, crossed round ? x indented <? and conse- 

 quently got no change of form. 



Cotyledons seen through coat. 



Ordinary dominance of round. 



|| This is an extraordinary statement to be given as a general 

 truth. There are sometimes indications of this kind, but certainly 

 the facts are not usually as here stated. 



1 If we were obliged to suppose that this is a matured conclusion 

 based on detailed observation it would of course constitute the most 

 serious "exception" yet recorded. But it is clear that the five 



