Vol.. 7, 1921 
GENETICS: A. F. BLAKESLEE 
151 
TABLE 3 
Occurrence oe New Globe Mutations prom Mutant Parents 
MUTANT SELFED MUTANT X NORMAL NORMAL X MUTANT 
SEED 
Of nt 
70 Gh. 
SEED 
SI 
JED 
PARENT 
PAR. 
NOR. 
GLOBES 
PAR. 
NOR. GLOBES % GL. 
PAR. 
NOR. 
GLOBES % GL. 
SZ VjlIlcCLLlcl 
968 
4 
0.41 
5 
389 
1 
0.26 
3 
591 
1 
0.17 
T^ni r\ c A*f"t* i n 
X UllXoC L LICb 
var. Wiry 
2 
189 
0 
1 
15 
0 
1 
225 
1 
0.44 
Cocklebur 
20 
1859 
1 
0.05 
8 
1047 
1 
0.10 
6 
1167 
0 
Ilex 
8 
855 
0 
5 
538 
1 
0.19 
4 
975 
0 
Mutilated 
16 
871 
1 
0.11 
8 
351 
0 
4 
552 
2 
0.36 
Sugar Loaf 
8 
413 
1 
0.24 
3 
367 
0 
1 
197 
0 
Rolled 
8 
705 
1 
0.14 
2 
222 
4 
1.80 
1 
245 
1 
0.41 
Reduced 
6 
707 
2 
0.28 
1 
127 
1 
0.78 
1 
215 
0 
Buckling 
8 
856 
1 
0.12 
1 
106 
0 
1 
246 
0 
Glossy 
7 
897 
1 
0.11 
1 
143 
0 
1 
253 
0 
Microcarpic 
18 
994 
1 
0.10 
5 
178 
0 
4 
353 
0 
Spinach 
13 
625 
8 
1.26 
3 
187 
4 
2.09 
2 
377 
0 
Totals 125 
9939 
21 
0.211 
43 
3670 
12 
0.326 
29 
5396 
5 
0.093 
=±=.031 =±=.064 =±=.028 
Percentage difference between offspring from mutant selfed and mutant x normal 
= 0.115 =«= 0.071. Diff./B. Diff. = 1.62. 
Percentage difference between offspring from mutant x normal and normal x mutant 
•= .233 =±= .070. Diff./B. Diff. = 3.33. 
which is the lowest average for any of the Datura mutants of this type yet 
investigated. Normal plants show only about 2.7 % of defective grains. 
Before the cause of the Globe mutation was discovered, an attempt was 
made to increase by selection the proportion of Globes in the offspring of 
selfed Globe parents. Globes were accordingly inbred for ten generations 
but the proportion of mutants and normals in the offspring was not notice- 
ably affected. 
Inasmuch as the Globe is one of the most readily recognized of all the 
Datura mutants and has been sought for in our cultures since its first ap- 
pearance in 1915, it is possible to give more reliable figures in regard to the 
frequency of its new appearance than could be done for the mutants dis- 
covered later. In table 2 is summarized the occurrence of Globe plants in 
offspring from selfed parents of the 19 different main lines. The various 
lines have the color, spine and node characters indicated in the table. It 
is seen that new Globe mutations have occurred in all the lines considered 
together in about 0.05% of the offspring which is about one out of 2000 
individuals. The offspring from crosses between main lines have shown 
new Globe mutations in about the same proportion as in the main lines 
themselves. 
We have just discussed the occurrence of Globe mutations from normal 
parents. It will be of interest to consider the occurrence of this mutant 
from parents belonging to the other mutant forms. In table 3 are shown 
