74 
A. S. Horne. 
this difference in size of the corolla was due to local soil-differences, 
plants of each kind, labelled B and A respectively were chosen, 
removed from the soil, and after the roots had been well washed, 
potted in a soil compost consisting of a mixture of sand, leaf-mould 
and loam. All the flowers of approximately the same age in each 
plant were measured before removal from the soil—in the case of 
the corolla, the diameter in millimetres when outspread and the 
width of the petal-lobe at its widest part. The average dimensions 
on June 6th, 1912, were as follows:—form B, corolla diameter 
14 to 15 mm.: width of petal-lobe 1 to F5 mm.; form A, average 
corolla diameter, 8 to 9 mm.; width of petal-lobe, ’8 to 1 mm. 
The plants were then placed in the greenhouse adjoining the 
laboratory, where they soon recovered from the effects of trans¬ 
planting. A photograph of specimens of the A and B forms, after 
their recovery, is reproduced in Fig. 1. 
Fig. 1. Photographs of the A and B forms of Stellaria graminea. For 
description see Text, 
