The Inheritance of Quantitative Characters in Maize 99 
That neither of the F 2 families and none of the F 3 's had any 
plants that were as late as the Missouri dent plants of 1911 is 
perhaps not strange when it is remembered that the original 
parent plants were representatives of commercial strains which 
had not been previously self-pollinated and when it is also re- 
called that the lots representing the two parent varieties were 
not descended directly from the plants used as parents of the 
cross. That the parent varieties were heterozygous for time of 
blossoming as well as for various other characters is indicated 
by the fact that one of the lots grown in 1911 was considerably 
earlier than the other. It is possible that the single gamete from 
Missouri dent, which by union with a gamete from Tom Thumb 
pop gave rise to F 2 family 510 and to all the F 3 families, lacked 
some of the factors for long-continued growth that were pres- 
ent in the parents of the lots used later to represent Missouri 
dent, [t might further be supposed that the 1910 representatives 
of Missouri dent were forced into abnormally early blossoming 
by the hot dry weather of that summer. It would then still re 
main to be explained why the weather of 1910 in Nebraska 
should make Missouri dent plants unusually early and at the 
same time cause many of the later F 2 plants to be unusually 
late, as was assumed before. Or perhaps it will be as necessary 
to explain why the weather of 1911 in Massachusetts delayed 
the blossoming of Missouri dent and at the same time hastened 
the blossoming of the later F 3 families. 
In this connection it should not be forgotten that too high a 
temperature, particularly if associated with extreme dryness, 
may retard the development of plants not adapted to such con- 
ditions while hastening the development of other sorts of plants. 
We do not know that diverse sorts of corn actually respond in 
these different ways to unusual conditions, but the possibility is 
worth considering. Is it possible that an early corn like Tom 
Thumb pop, adapted to growth in the North, may develop quite 
as rapidly at moderate temperatures as at higher ones, i. e., the 
optimum temperature for it is low, while a late variety, which 
can only be matured in the South, may be greatly retarded in 
its development by anything short of high temperatures? And 
is it possible also that this assumed adaptation to growth at 
somewhat low temperatures might be inherited independently of 
other genetic factors for earliness. so that F 2 segregates might 
rank quite differently in earliness in different seasons? The 
topic should not be dismissed without referring back to the 
records of height of plant of these same lots of corn (Table 29). 
Here we meet the suggestive facts, first, that the 1911 Missouri 
dent families were not so tall as the 1910 plants from which 
they came, tho it took them much longer to complete their 
