Vol. 7, 1921 
GENETICS: A. F. BLAKESLEE 
149 
The Globe mutant differs from normals apparently in all parts of the 
plant. It shows a complex of characters readily recognized, whether the 
plants in question have purple or white flowers, many or few nodes, and 
spiny or smooth capsules. Globes, like other mutants of this type, are 
slower in growth than normals ; and in competition with normals are liable 
to be crowded out by them. 
TABLE 1 
Globes Selfed and Crossed Reciprocally with Main Line Normals. Plants 
Pollinated in Greenhouse, 1916-17. Records Taken in Seed Pans in Green- 
house, 1917-18 
ORIGIN 
SEEDS 
SEEDS 
SEEDLINGS 
PER CENT 
GLOBES 
NORMALS 
PER CENT 
RATIO 
OF SEED 
PARENTS 
PLANTED 
SEEDLINGS 
GLOBES 
g: n 
Globe 
27 
3015 
1782 
59.10 
400 
1382 
22.45^0.676 
1:3.46 
Selfed 
Globe x 
27 
2628 
1935 
73.63 
500 
1453 
25.84 ±0.671 
1:2.87 
Normal 
Normal 
x Globe 27 2771 1812 65.39 53 1759 2.92 ±0.269 1:33.19 
Percentage difference between offspring from Globe Selfed and from Globe x normal 
= 3.39 =*= 0.935. Diff./E. Diff.= 3.59. 
Early breeding work with the Globe indicated that the manner of its in- 
heritance was not in accord with any simple Mendelian interpretation. A 
more extensive series of selfs and crosses was therefore carried out in order 
to determine more accurately the extent to which the Globe complex could 
be transmitted. In table 1 is presented a summary of the experiment. 
In this table are given the number of seeds planted and the percentage of 
recordable seedlings which they produced. It is obvious that a difference 
exists between the inheritance through the male and that through the fe- 
male parent. The egg cells of Globes, whether fertilized by Globe pollen or 
by pollen from normal plants, transmit the Globe complex to only about 25 
per cent of the offspring. Globe pollen, when used on normal plants, trans- 
mits the character to only about 3 per cent of the offspring This figure, 
though small, is too large to be accounted for by the occurrence of new Globe 
mutations, in view of the rarity of Globes from normal parents in com- 
parable material. The normal offspring of Globes seem to be true, 
normals so far as their breeding behavior is concerned. 
If 3 % represents the average number of Globe pollen grains which trans- 
mit the mutant character, we should expect a higher proportion of Globe 
offspring when Globe pollen is used than when pollen from normals is used 
on Globe females. The reverse, however, is actually the case, and Globes 
selfed produced a lower percentage of mutant offspring than Globes pol- 
linated by normals. The explanation may possibly be connected with a 
difference in vitality between seedlings produced by self and those pro- 
duced by cross pollination. The fact is at least suggestive that a lower per- 
