308 
Breedhuj Experiments with Foxgloves 
It will be of interest to compare these figures with those that would be expected 
if the character behaved as a Mendelian unit. In the experimental results it will 
be noticed that all plants showing any tendency for a crown are grouped together 
as opposed to the plants exhibiting no such tendency. 
To obtain the theoretical figures, and speaking in Mendelian terminology, it 
will be necessary to make certain assumptions as to the homozygous or heterozygous 
nature of the parent plants with regard to the presence or absence of a crown. 
The absence is dominant over the presence of a crown. 
In the cases of parents A, C (1), C (2) and B (4) we have experimental evidence 
of the gametic nature of the plants. Reference to the above table will show that 
A and C (1) are pure recessives (families I a and I), C (2) is heterozygous (family X), 
and B (4) almost certainly homozygous dominant (family IV). For the other 
parents we assume that B (3) and B (4) are homozygous dominant, N (1) pure 
recessive, and C (3) and N (2) heterozygous. 
With these assumptions, which are warranted by the behaviour of the parents 
in the various crossings, we can calculate the theoretical expectation for each 
family. The totals, to the nearest whole figure, are 83 plants crowned and 
104 plants not crowned. The experimental result as shown above gives the 
same figures. In the light of other investigations this identity between the 
theoretical expectation and experimental result is to be regarded, of course, as 
unusual and accidental. 
Of the 83 plants with a crown or a tendency for a crown the number in each 
grade is given below: 
100 % 
75% 
50% 
25% 
Total 
62 
8 
1] 
2 
83 
In the various crossings of crowned parents and non-crowned parents there is 
thus a marked tendency for the character to be transmitted in its entirety or not 
at all. Notwithstanding this fact it nevertheless appears that the character can 
be diluted ; for example in cross no. XI, A (crowned) ? x 6* (3) (ordinary) S, we have : 
Crowned 
Not 
100 % 
75% 
50% 
25% 
crowned 
2 
4 
3 
1 
7 
Thus, although the character appears to be capable of blending yet it is usually 
transmitted as a simple Mendelian unit. 
