76 
A. S. Horne. 
Two points may be noted:—(1) that the corolla of only one 
form (B) responded to a changed environment and produced 
very small flowers under the experimental conditions chosen ; (2) that 
the corolla of form B varied in size during the season. It is natural, 
therefore, from these results, to expect some variability in the size 
of the corolla of form B, in nature, according to the conditions 
under which the habitat is placed. 
A large number of observations on plants in the field had now 
been made and the dimensions of the flowers of equal age on each 
plant carefully recorded. The variability in the different parts of 
the flower may be described as follows:— 
The sepals. These are slightly boat-shaped and of triangular 
outline, with three veins and a membranous margin. In measuring, 
each sepal was flattened and the width estimated across the widest 
portion—care being taken to measure from margin to margin. 
Each sepal is prolonged into a hair-like extremity so that a slight 
error is introduced in length measurements where the hair is broken 
or withered. The sepals do not vary in size to the same extent as 
the petals and stamens. The dimensions, in the plants studied, 
vary between 5 x l f 3 mm., 4'5 x 1*8 mm., and 3x1 mm. Both 
long and short sepals may be either wide or narrow, such as 4‘5 x 
1-8 mm. and 3 x 1*6 mm., or 5 x 1*3 mm. and 3x1 mm. Longer 
and shorter sepals are usually found associated with the larger or 
smaller corollas in the large and small flowered forms respectively. 
The corolla. The petals are divided nearly to the base in all 
the specimens examined. It was found most convenient to take 
two measurements: (1) the diameter of the corolla; (2) the width 
of the petal-lobe. The diameter of the corolla was measured when 
the petals were outspread in a plane passing through the bases of 
the styles. This character, choosing flowers of approximately equal 
age, in each case, varied between 15 and 5 mm.; thus, the corollas 
in one individual measured 14 to 15 mm.; another, 12 to 13 mm.; 
another, 7 to 8 mm. in diameter, and so on. The width of the petal- 
lobe was measured in its widest portion. This character sometimes 
varies in the same flower, but in most plants it is more uniform. 
It varies from 2 to *6 mm.; measuring, in one individual, 0*8 to 1 mm.; 
another, 1 to 1‘2 mm.; another, 1’4 mm.; another, 1*8 mm., and 
so on. 
The flowers, of course, present different appearances in the field 
according to the dimensions of the corolla, but these appearances 
