500 
H. A. ALLARD 
Hayes, East and Beinhart^ from a statistical study of some New 
England types in the field, came to the conclusion that environmental 
conditions have little effect upon the number of leaves produced in 
the field. 
Although in the writer's experiments it is indicated that severe 
stunting brings about a suppression of the flower branches of the 
terminal whorl, it is probable that the terminal bud does not appear 
until the number of nodes preceding it and predetermined in the 
embryo have developed. 
From field experiments with tobacco East and Hayes (Am. 
Naturalist, 48: 5-48, previously cited) have concluded that the con- 
ditions under which the mother plants grow may determine the 
number of leaves in the embryo within the normal limits of fluctuation. 
To establish this point beyond question, however, it will be necessary 
to determine all the nodes produced by the plants beginning from the 
cotyledons. It is clear that results based upon counts from the first 
bald sucker may not be entirely free from error. From the data for 
the experiments given in Tables I and H, it appears that the position 
of the first bald sucker has not been constant under all conditions. 
Thus, counting from the cotyledons up to, but not including, the 
first bald sucker, the normal plants in experiment I produced an 
average of 28.4 leaves. In the second experiment the average for a 
similar count was only 26.4, amounting to a difference of two leaves. 
Counting all the nodes below the terminal blossoms, however, the 
average for both sets of plants was the same, namely 32.4 for the 
plants in experiment I and 32.4 for those which averaged only half 
as tall in experiment II. As the limits of minimum growth are 
approached it is evident that the first bald sucker can no longer be 
relied upon for comparative studies. 
Between the limits of minimum growth and maximum growth all 
degrees of ontogenetic expression with respect to capsule and seed 
development may be noted. Reduction in size of plant is accompanied 
by a more or less proportionate decrease in the number of seed pods 
borne by the plant. 
It has not yet been shown that the physiological environment 
2 Hayes, H. K., East, E. M., and Beinhart, E. G., " Tobacco Breeding in Con- 
necticut." Conn. Agr. Exp. Sta. Bull. 176: 40-42. May, 1913. See also, East, 
E. M., and Hayes, H. K. "A Genetic Analysis of the Changes Produced by Selec- 
tion in Experiments with Tobacco." American Naturahst, 48: 5-48. 1914. 
