June n, 1917 
Hybrids of Zea ramosa and Zea tunicaia 
393 
Table IV .—Characters of staminate and pistillate inflorescences of the tunicata-ramosa 
group of F 2 plants of Zea ramosa X tunicaia hybrid 
Character of staminate inflorescence. 
Character of pistillate inflorescence. 
Ra¬ 
mosa. 
Without 
cauli¬ 
flower. 
Partial 
cauli¬ 
flower. 
Completely 
cauli¬ 
flower. 
Total. 
Ramosa . 
Without cauliflower. 
24 
II 
2 
24 
14 
21 
1 
Partial cauliflower .. 
3 
19 
1 
Completely cauliflower. 
Aborted. 
Total .. 
37 
23 
60 
If the second-generation plants are examined for each of the parental 
types separately, there is seen to have been a simple 1 to 3 segregation 
in both instances. One-fourth of the total number of plants are ramosa 
and three-fourths non -ramosa (observed, 79 to 247; expected, 81.5 to 
244.5). One-fourth are nontunicate and three-fourths tunicate (ob¬ 
served, 80 to 246; expected, 81.5 to 244.5). The distinction between 
half and full tunicate could not be made when these characters were 
combined with the ramosa character. The various combinations of 
parental characters, occurring as they do in the normal dihybrid ratios, 
show that the tunicaia and ramosa characters are not genetically corre¬ 
lated. 
In addition to the notes on the inflorescences, the height of each 
plant was recorded. From these measurements it develops that there 
were consistent differences in the height of the segregated groups. The 
averages are given below: 
Type of plant. 
Normal. 
Ramosa . 
Half tunicate... 
Tunicata-ramosa 
Full tunicate... 
Height (cm). 
. 22 1±2. 7 
. I95±2. 2 
■ i 95 ± 2 . 4 
• 191^:2. 6 
• i7i±2. 7 
These differences in height can hardly be explained as differences in 
vigor due to different degrees of heterozygosity of the characters con¬ 
cerned, since the ramosa and half-tunicate groups, which are of the 
same and an intermediate height, are at once the least and most hetero¬ 
zygous of all the groups. 
ORIGIN AND SIGNIFICANCE OF CAULIFLOWER INFLORESCENCE 
In our experiments the appearance of cauliflower in the inflorescence 
seems definitely confined to plants in which both the tunicaia and ramosa 
characters are, as it were, endeavoring to come into expression—that is, 
