ne 
Te geeeet Saree 
ae Sa 
ide a 4 
49 BULLETIN 754, U. 8. DEPARTMENT OF AGRICULTURE. 
a failure of dominance in some of the seeds or a deficiency on the 
part of the male parent of gametes bearing one of the color factors. 
This deficiency could be due to a differential death rate, a les- 
sened vigor resulting in a slower growth of the pollen tube, or to a 
failure of the plant to produce gametes in equal proportions. It will 
be recalled that the plants heterozygous for colored aleurone are pre- 
sumed to be making two classes of gametes, CR and C7; a deficiency 
of white seeds when plants of this nature are used as male parents 
on plants making oné class of gametes (C7) indicates a deficiency of 
gametes bearing (7. *The relations of those ears are shown in figures 
4 and 5. . 
The large deviation for the total seeds of the 29 ears is due to a 
great extent to the three ears that deviated by more than seven 
times the probable error. These ears must stand as definite excep- 
S754 
While 
Fed l6535 VAL 
Fic. 5.—Diagram showing the relations of ears Nos. 1653, 1703, and 1702. 
tions to the general agreement of the material with theory, but since 
they stand rather apart from the remaining ears it may be well to 
exclude them and then examine the totals. 
Omitting the data relating to these ears from the total number of 
seeds for the 29 ears, the percentage of white becomes 48.5. This 
deviation is 4.6 times the probable error and is still too large to 
occur as the result of chance. That there is a tendency toward too © 
few white seeds when heterozygous colored plants are used as male 
parents is demonstrated for this group, even omitting the ears with 
obviously aberrant ratios. 
