ABNORMALITIES IN INFLORESCENCE OF SPIRAEA VANHOUTTEI 633 
The whole series of available data may be taken to indicate with 
remarkable consistency that the bimodal nature of the distribution 
of number of flowers per pedicel is not due to heterogeneity of material, 
so far as this may originate from the combination of inflorescences 
derived from differentiated individuals. It represents, therefore, the 
resultant of some group of factors innate in the individual. 
Having eliminated the possibility of an influence of the individual 
plant as a determining factor of the peculiar frequency distribution, 
it seems worth while to enquire whether any characteristic of the 
inflorescence itself may have an influence upon the distribution of 
Table V 
Bimodal Distribution of Number of Flowers per Pedicel in Inflorescences with Various 
Numbers of A bnormal Flowers per Pedicel 
Total Abnormal 
Nu 
mber of Flowers Produced by Abnormal Pedicels 
Total 
Pedicels 
2 
3 
4 
5 
6 
7 
8 
9 
10 
II 
12 
I 
30 
8 
5 
8 
12 
18 
28 
12 
6 
3 
130 
2 
17 
13 
9 
8 
19 
33 
31 
35 
17 
4 
186 
3 
27 
13 
13 
12 
32 
52 
63 
50 
28 
4 
294 
4 
21 
7 
20 
18 
42 
58 
62 
62 
33 
9 
332 
5 
34 
15 
13 
19 
40 
66 
131 
103 
41 
12 
I 
475 
6 
24 
16 
4 
15 
31 
56 
89 
91 
47 
10 
I 
384 
7 
26 
6 
9 
23 
49 
79 
132 
96 
64 
44 
12 
476 
8 
15 
4 
4 
II 
20 
50 
80 
42 
13 
I 
304 
9 
16 
7 
7 
7 
29 
54 
59 
59 
20 
3 
261 
10 
8 
2 
I 
II 
20 
54 
67 
46 
16 
5 
230 
II 
2 
3 
2 
12 
16 
29 
28 
6 
99 
12 
I 
I 
3 
I 
4 
13 
10 
2 
I 
36 
13 
2 
7 
20 
42 
26 
18 
2 
117 
14 
2 
I 
4 
15 
20 
12 
I 
56 
16 
I 
I 
5 
5 
4 
16 
Total 
225 
94 
87 
139 
319 
580 
851 
698 
321 
79 
3 
3,396 
the number of flowers per pedicel. It is quite conceivable, for example, 
that the inflorescences which are the most highly abnormal as measured 
by the total number of abnormal pedicels, should have a larger number 
of flowers in their secondary umbels than those which are only very 
slightly abnormal. The combination of a series of inflorescences, 
some only slightly abnormal and others highly abnormal, might, under 
such conditions, result in a bimodal distribution of flower number in 
the series of pedicels from the combined inflorescences. 
Table V shows the number of flowers per pedicel in the 3,396 
abnormal pedicels produced by the 747 inflorescences examined from 
