412 De Vries . — On Biastrepsis in its 
the June sowing. In contrast with this, the spring-sowings 
gave 34-37 per cent, of twisted stems. 
I conclude, therefore, that late sowing does not allow the 
plant sufficient time in which to attain normal vigour in the 
rosette-stage. Hence, when the shoots are thrown up, they 
are too weakly to develop spiral phyllotaxis. This result 
accords fully with those obtained in my observations on the 
effects of too limited space and bad soil. 
E . Autumn-Sowings in the Open. 
I began an experiment on September 11, 1891, which may 
be regarded as a control to the summer-sowings. The seed- 
lings which are produced in a sowing so late in the season do 
not throw up their shoots in the following year, but remain in 
the rosette-stage, the plants growing vigorously until the 
following autumn. They do not throw up their shoots until 
the third year. The lateness of the sowing has, therefore, the 
effect, not of weakening, but of materially invigorating the 
plants. 
At the beginning of the first winter the young plants had 
only two or three pairs of leaves, which were not much more 
than 3 cm. in length. It is known that the throwing up of 
the shoot of biennials in general is the result of stimulation, 
and that this stimulation is given by the winter. Indeed, 
when Rape is sown early, this effect may be produced by 
the late night-frosts. But if the plants are too young they 
appear not to be susceptible to this stimulation. This is 
a phenomenon which has been too much overlooked by 
physiologists. 
In the middle of September, 1892, just one year after 
sowing, I examined the plants. There were twenty-three of 
them in a small bed of 2 square metres area. Not one of 
them had thrown up a shoot ; but ten of them (44 per cent.) 
showed spiral phyllotaxis in the heart of the rosette, and four 
had three-leaved whorls. 
