1059 
between breadth and colour. For in the second generation there 
occur among the white, as well as among the blue flowers, narrow, 
broad and intermediate petals of every kind, although the white 
P-variety is narrower than the blue. The factors for broadness and 
for colour evidently follow Merper’s law of segregation independently. 
On the other hand the behaviour of the breadth and its relation 
to colour is quite different in tbe cross between the common blue 
(7 mm.) and the narrow-petalled white flax (3.3 mm.). These two 
varieties, like the preceding pair, differ in breadth as well as in 
colour. Here, however, all the blue descendants agree in breadth 
with the common blue flax and all the white ones with the narrow- 
petalled white. Although the two P-varieties, as in the two previous 
crosses, differ in breadth, there are here no transitions. Two sharply 
separated groups arise, one with broad blue petals and the other 
with narrower white ones, each agreeing with one of the two 
varieties crossed. In this case there is therefore a connection between 
breadth and colour, in contradistinction to the crosses previously 
discussed; the broader petals are always blue, the narrower ones 
always white. 
Knowing only the phenomena occurring in this cross, one would 
doubtless feel convinced, that one and the same factor, or a group 
of completely coupled factors produces here simultaneously the 
superior breadth and the blue colour of the petal. We learn, however, 
from the investigation of another cross, namely between the Egyptian 
(13.4 mm.) and the narrow-petalled white flax (3.3 mm.) which also 
differ both in colour and in breadth, that the relation of breadth to 
colour is a different one, although these factors are not wholly 
independent either, as was apparently the case in the crossings 
discussed first. 
In this cross between the Egyptian flax and the narrow-petalled 
white variety, the first generation has blue petals intermediate in 
breadth between those of the parents. In the second generation the 
relation of white and blue individuals as to the breadth differs from 
that in the crosses already discussed. 
Of 300 different white-flowered #-plants the breadth of the petals 
of one flower was determined and also of 300 plants with blue 
flowers. Whereas the petal-breadth in the narrow P-variety varies 
from 2.1 to 4.2 mm. and in the Egyptian flax from 10.5 to 16.4 mm., 
the white /’,-plants gave for the breadth 2.1 to 10.4 mm. and the 
blue F‚-plants 5.7 to 16.2 mm. 
The white #-plants in general have much narrower petals than 
the blue. Hence two groups are formed, one with narrow white 
