W. F. R. Weldon 
251 
The behaviour of these races is much more exactly in accord with the state- 
ments of Laxton. In 1866, the year in which Mendel's paper was published in 
printed form, Laxton published a short summary of the results gained during 
many years of work upon Peas, which shows that his experience was altogether 
different from that of Mendel. He says of the colour and character of the 
seed : 
" The results of experiments in crossing the Pea tend to show that the colour 
" of the immediate offspring or second generation sometimes follows that of the 
" female parent, is sometimes intermediate between that and the male parent, and 
" is sometimes distinct from both ; and although at times it partakes of the colour 
"of the male, it has not been ascertained by the experimenter ever to follow the 
" exact colour of the male parent. In shape, the seed frequently has an inter- 
" mediate character, but as often follows that of either parent. In the second 
" generation, in a single pod, the result of a cross of Peas different in shape and 
" colour, the seeds are sometimes all intermediate, sometimes represent either or 
" both parents in shape or colour, and sometimes both colours and characters, with 
"their intermediates, appear. The results also seem to show that the third 
"generation, that is to say, seed produced from the second generation or the 
"immediate offspring of a cross, frequently varies from its parents in a limited 
" manner, usually in one direction only, but that the fourth generation produces 
" numerous and wider variations, the seed often reverting partly to the colour and 
"character of its ancestors of tlie first generation, partly partaking of the various 
" intermediate colours and characters, and partly sporting quite away from any of 
"its ancestry." (Laxton, No. 19, p. 156.) 
In a review of his own work, nearly a quarter of a century later, Laxton says 
again : " By means of cross-fertilization alone, and unless it be followed by careful 
" and continuous selection, the labours of the cross-breeder, instead of benefiting 
" the gardener, may lead to utter confusion." (No. 20.) 
These statements show that the phenomena of inheritance in cross-bred Peas, 
as Laxton observed them, were far more complex than those described by Mendel ; 
but they do not preclude the possibility of a simple segregation, such as Mendel 
describes, in particular cases. Such cases of simple segregation have been 
described in Peas by both Correns and Tschermak in the papers already cited. 
The proportions of dominant and recessive individuals, found by Correns in his 
later generations, were in accord with Mendel's results; those found by Tschermak, 
as he himself points out, were extremely improbable, on Mendel's hypothesis. 
Taking these results together with Laxton's statements, and with the evidence 
afforded by the Telephone group of hybrids, I think we can only conclude that 
segregation of seed-characters is not of universal occurrence among cross-bred Peas, 
and that when it does occur, it may or may not follow Mendel's law. The law of 
segregation, like the law of dominance, appears therefore to hold only for races of 
particular ancestry. In special cases, other foi-mulae expressing segregation have 
