FACTORS INFLUENCING FLOWER SIZE IN NICOTIANA 367 
little or no attention in the greenhouse and the average spread of their 
flowers was over 8 mm. smaller and the length of corolla over 2 mm. 
smaller than the spread and length respectively of flowers borne on 
plants in the field in 1912, and still smaller than the flowers of Fi H38 
in 1913. 
With reference to the influence upon flower size of favorable and 
unfavorable greenhouse treatment our results are at variance with 
those of East. While in his cultures the size of flower did not vary 
under different conditions of greenhouse culture, our plants, under 
conditions which may be compared with good and poor greenhouse 
treatment, did show a distinct modification as to flower size as well 
as in respect to size of vegetative characters. In a series of pot 
experiments in which plants of N. sylvestris were treated with varying 
amounts of sodium nitrate, the plants receiving what seemed to be 
the optimum amount of salt produced larger flowers than the plants 
which received the maximum and minimum amounts of nitrate. 
Thus two plants which were treated with very nearly the same amounts 
of sodium nitrate showed an average difference in spread of about 3 
mm. and about the same average difference in length. It is interesting 
in this connection to note that the plant treated with less nitrate 
produced flowers nearly 3 mm. smaller as to spread and over 2 mm. 
smaller as to length of corolla as compared with the flowers of plants 
of N. sylvestris grown on poorer land, and correspondingly smaller 
when compared with the size of flowers borne on plants grown in richer 
garden soil; i. e., 8.12 mm. in spread and 12.28 mm. in length. 
Now these variations in flower size under varying conditions at- 
tending development are a matter of common knowledge. It need 
only be mentioned that it is commonly recognized in horticultural 
practise that certain conditions of soil and treatment are conducive 
to the development of flowers of maximum size, and these conditions 
are often stated very definitely for particular plants. These facts 
have not escaped the attention of biometricians who have, however, 
for the most part concerned themselves with the discrete variations of 
composite flowers. Other types of flowers have, however, been con- 
sidered, as for example Ficaria ranunculoides Moench. For this 
species MacLeod (1899) determined the number of stamens and the 
number of pistils in each of a series of flowers borne by certain plants 
at the beginning of the flowering season, and again in a series of 
flowers at the end of the season. The observations were made on the 
