Principles of Heredity 145 



though Dwarf Imperial, in a form which I can feel sure 

 is Seton's form, I have not succeeded in seeing ; but 

 from Vilmorin's description that the peas when ripe are 

 "franckement verts" I feel no doubt it was a green pea 

 with a green skin. If it had had a transparent skin this 

 description would be inapplicable. Having then a green 

 skin, which may be assumed with every probability of truth, 

 the seeds, even though the cotyledons weje yellow, might, 

 especially if examined fresh, be indistinguishable from those 

 of the maternal type. Next from the fact of the mixture 

 in the second generation we learn that the semi-transparent 

 seed-coat of the paternal form was dominant as a plant- 

 character, and indeed the coloured plate makes this fairly 

 evident. It will be understood that this explanation is 

 as yet suggestive, but from the facts of the second genera- 

 tion, any supposition that there was real irregularity in 

 dominance in this case is out of the question*. 



(3) Tschermak's exceptions. These are a much more 

 acceptable lot than those we have been considering. 

 Tschermak was thoroughly alive to the seed-coat question 

 and consequently any exception stated as an unqualified 

 fact on his authority must be accepted. The nature of these 

 cases we shall see. Among the many varieties he used, 

 some being not monomorphic, it would have been sur- 

 prising if he had not found true irregularities in dominance. 



(3 a) Buchsbaum case. This variety, growing in the 

 open, gave once a pod in which every seed but one was green. 

 In stating this case Professor Weldon refers to Buchsbaum 



* Since the above passage was written I find the "Imperials" 

 described in "Report of Chiswick Trials," Proc. R. Hort. Soc. 1860, 

 i. p. 340, as " skin thick " ; and on p. 360 " skin thick, blue " ; which 

 finally disposes of this " exception." 



B. 10 



