COMPLICATIONS ARISING IN THE CROSS-BREEDING OF STOCKS, 147 
for example, has the peculiarity that the singles are white while the 
doubles are cream. Experiments are now in progress with a view to 
determining to what extent colour is affected by the occurrence of 
doubling. Apart from this possible complication the general scheme 
underlying these various results is now clear, and we can now perceive 
that many which at first sight appeared irregular and paradoxical are in 
reality orderly and consistent—due to the existence of definite relation- 
ships between factors which are typically Mendelian in their behaviour. 
CorRRIGENDUM.—Since this paper was printed Mr. Doncaster has called 
attention to an error in the account given here and in Report to the 
Kyolution Committee of the Royal Society, III. A study of the figures 
and diagrams shows that the postulate of two hoariness factors (H and K) 
is unnecessary, and that one (K), in addition to the colour factors, is 
sufficient to represent the whole series of phenomena. This unfortunate 
mistake arose through a misinterpretation made in earlier stages of the 
analysis, which was carelessly retained after each of the results on which 
it was based had been otherwise elucidated. 
DISCUSSION. 
Professor Tschermak asked whether Miss Saunders began with 
uniform whites or whites extracted from other colours. 
Miss Saunders said they were all pure whites belonging to the same 
strain. There were, of course, as she understood, different varieties of 
whites. For example, by crossing an ordinary white Matthiola incana 
with a glabrous red—a white hoary form with a glabrous red—they got in 
F, whites, which were different from the whites which they got if they 
crossed a white glabrous with a cream glabrous. 
The President said that Brompton stocks did not behave exactly as 
did Ten-week stocks. 
Miss Saunders added that there was one other point she had intended 
to mention, and that was that there appeared to be a curious connection 
between flower colour and the occurrence of doubling. There was a well- 
known strain of Ten-week stocks in which the singles were all-white and 
the doubles all-cream colour, and there appeared to be a curious coupling 
between the character of the flower and the colour factor. As to that, her 
experiments were still in progress. 
The President said the matter was very complicated. The distribution 
of doubling was the most difficult of all cases they had heard of to bring 
under any kind of systematic Mendelian scheme. They had a single 
variety throwing off the double form, and yet the double form in stocks 
did not set seeds. They were given off by single stocks which did set 
seeds, and in the general run Miss Saunders’s work showed that the 
double was recessive to the single. But another remarkable paradox was 
that some of the single varieties might give as much as 80 per cent. of 
doubles. How that was to be dealt with as a question of physiology was 
at present entirely unknown. They all hoped that Miss Saunders would 
succeed in solving the problem. 
K 2 
