HOMOTYPOSIS IN THE VEflETABLE KINGDOM. 
335 
of them, and excess or defect from the average number of fertile seeds would depend 
only on the constitution of the individual plant. It would seem accordingly that in 
the case of cross-fertilisation ample visitation was a sine qua non, and this led me to 
select broom in the first place. 
Broom (Cytisus Scoparius), Danhy Dale .—-We collected 10 pods from each of 120 
broom bushes. These were growing within some quarter of a mile of each other, on 
the roadside at Botton, towards the head of Dauby Dale, Yorkshire. 
I roughly estimated that if abortive seeds were to l)e included, 10 would be about 
the modal number of ovules ; the actual average of fully developed seeds in 1200 pods 
was 9'6425, with a modal value at 9, so that some 6 to 7 seeds failed of fertilisation 
on the average in each pod. The following is the frequency distribution of the seeds 
in the pods :— 
No. of seeds . 
1. 
2. 
3. 
4. 
5. 
6. 
7. 1 8. 
i 
9. 
10. 
11. 
12. 
13. 14. 
15. 
16. 
17. 
j 
18. 19. i 
20. 
Total. 
Frequency . 
8 
15 
29 
47 
.54 
77 
98 j128 
1 
136 
134 
103 
100 
98 67 
48 
33 
17 
5 I- 
1 
1200 
I came across no pods with an entire absence ot seeds, although such may exist. I 
refer to this because the reader might think that such were discarded. The distribu¬ 
tion is fairly regular, but it is clear that the variation is very large, the distribution 
being very flat toj)ped. As in nearly all the cases that I have dealt voth in tills 
memoir, it is markedly skew. I reserve, however, for the present the full considera¬ 
tion of variation in the vegetable world, as my data extend far l)eyond the material 
considered in tliis paper, which is limited to the cases in which tlie homotypic corre¬ 
lation has also been worked out—a far more laborious enquiry. I would only remark 
that among plants and trees I know of nothing appi'oximating even to the “ normal 
law,” and that in many cases we appear to have mixtures of local races hardly yet 
differentiated by the botanist. 
The following table gives the constants for broom :— 
B) 'oom. Seeds in Pods. 
Number of 
Mean No. 
of seeds. 
S. T). of 
seeds. 
Coefficient 
of 
variation. 
S. I). of 
array. 
Percentage 
variation. 
Correla¬ 
tion. 
Plants. 
Pods. 
Pairs. 
120 
1200 
10,800 
9 • 642.5 
± -0691 
.3 ■ 54655 
+ '0488 
36 • 7804 
3•22595 
90-96 
•4155 
[± -0161] 
The actual distribution of pairs is given in the table on the following page. It 
will be seen that some of the arrays are rather irregular, but in its results I look 
upon broom to be as satisfactory as any material I have dealt with. In the first 
place, the table fully bears out tlie conclusion drawn from the simple frequency 
