STUDIES ON MENDELIAN FACTORS IN AQUILEGIA VULGARIS 187 
It is seen that the wheigth of the seed is much correlated to the 
flower colour. The weight of 1000 grains of the dark-blue and the 
red types is much greater than that of the light-blue and the white. 
Any difference between the dark-blue and the red, or between the 
light-blue and the white is not to be seen. Consequently, only the 
red factor has an increasing influence on the size of the seed. The 
light-blue factor is quite insignificant in this character. 
It is true, one may remarks as to my discussion of the correlation 
between the flower colour and the size of the seeds that the number 
of individuals is too small. However, all the observations point in 
the same direction. Further, they are in agreement with the above 
mentioned cases of pleiotropism of the red factor and, therefore, I - 
think my interpretation is correct. 
The investigation of the pleiotropism of the red factor is probably 
not complete. On the contrary, it is very probable that the factor R 
has a great influence upon other parts of the plant. Thus the white 
flowers are not as large as the red, and their stems are presumably 
thinner. However, I had no occasion to investigate these characters. 
In Linum Tames (1915) has found that the germination of 
the white flowering plants, which had the factor C present, was very 
poor. This is not the case in Aquilegia, however. This form germi- 
nates as good as the coloured types. They agreed in this respect 
with the white form of Linum which has the factor B while the 
factor C is absent. 
Hatievist (1921) classifies the cases of pleiotropism in two 
classes, the isophene and the heterophene. In the first case the factor 
has a similar effect in different parts of the plant. The power of 
the red factor in Aquilegia of developing anthocyan in the flower as 
well as in the vegetative parts of the plant is then an isophene type 
of pleiotropism. 
The heterophene pleiotropism shows different effect in the diffe- 
rent organs. The flower colour factor C, found by Tammes (1916) 
in Linum, belongs to this latter group. The petals become crisp 
and more narrow, and the seeds lose their vitality when this factor 
C is present without the other fundamental colour factor, i. e. B. The 
red vein factor in Oenothera, discussed by HERIBERT-Nırsson (1915), 
also belongs here. Mention should also be made of the fatuoid and 
speltoid mutations in oats and wheats and the yellow colour factor 
in oats, which inhibits the formation of bristles (NiLsson-Exe 1911, 
1914 and 1917). Additional examples are easily found. We have 
