3 2 ° 
Journal of Agricultural Research 
Vol. XXV, No. 7 
brachytic variation arose. These Fj plants are normal also with respect 
to the other teratological characters. 
(3) In the prejugate generation three types of plants with respect to 
stature are found—normal, brachytic, and dwarf. These three stature 
groups occur in the ratio of 91314, when due allowance is made for the 
low survival value of dwarf plants, indicating that the double recessive, 
a combination of dwarf and brachytic, closely resembles the dwarf parent. 
This indication is confirmed when the self-pollinated seed of segregated 
brachytic plants is grown. 
(4) As was to be expected, some of the F 2 brachytic plants proved to 
be heterozygous for dwarf, their progenies comprising two types of 
plants—brachytics and dwarfs. These dwarfs represent the double 
recessive, being a combination of brachytic and dwarf, but are only 
slightly smaller than the dwarf parent of the original hybrid. They are 
found to have all the other characteristics of dwarf plants. 
(5) From their behavior it may be concluded that dwarf and brachytic 
are two independent variations, both expressed in reduced stature, the 
genes for which are located in separate chromosomes. 
(6) The analysis of the plants of the second generation with respect 
to all the characters which differentiate dwarf plants from the other 
groups shows clearly that the complex of characters associated in the 
dwarf variation is not inherited invariably as a unit. Thus, many of the 
plants of normal stature are found to have ears terminating in staminate 
spikes, or tassels with few or no branches, or short, broad leaves, and even 
a few were found with perfect flowered ears. Such behavior would 
indicate that the combination of characters comprising the dwarf varia¬ 
tion formed a linkage group with very low crossover values between some 
of the members. On the other hand, the plants of extremely short 
stature, easily distinguishable from the brachytic and normal plants as 
dwarfs, always had other dwarf characters, such as short, broad leaves, 
perfect flowered ears, and few tassel branches. These dwarf segregates, 
like their parent, also shed little pollen, though some of the F 2 segregates 
seem to have improved slightly in this respect. 
(7) From a consideration of the general features of such variations as 
anther ear, dwarf, and brachytic it is suggested that in maize, at least sev¬ 
eral and possibly all the chromosomes are identical, each having a com¬ 
plete assortment of genes for all the characters arranged in a similar order. 
Such a condition would arise through a reduplication of the chromosome 
number in much the same manner as that observed by Blakeslee in 
Datura (r). 
(8) The recurrence of degenerative variations is discussed and the 
hypothesis advanced that the survival of such stocks is due to the linkage 
relations of deleterious characters with factors favorable for growth. 
literature CITED 
(1) Blakeslee, Albert F. 
1921. TYPES OP MUTATIONS AND THEIR POSSIBLE SIGNIFICANCE IN EVOLUTION. 
In Amer. Nat., v. 55, p. 254-267. Bibliography, p. 266-267. 
(2) Collins, G. N. 
1918. TROPICAL varieties of maize. In Jour. Heredity, v. 9, p. 147-154, 
fig. i- 3 '• 
(3) Emerson, R. A. 
1911. GENETIC CORRELATION AND SPURIOUS ALLELOMORPHISM IN MAIZE. In 
Nebr. Agr. Exp. Sta. 24th Ann. Rpt., p. 59-90, 9 fig. 
