Relation to Cultivation . 
4i3 
Hence it appears that the effect of the prolongation of the 
rosette-stage is rather to increase than to diminish the pro- 
portion of abnormal plants. Moreover, this experiment leaves 
no doubt as to the correctness of the interpretation which 
I have placed upon the results of summer-sowing. 
F . Autumn-Sowings in the Greenhouse. 
The object of these experiments was so to accelerate, by 
cultivation in a greenhouse under favourable conditions of 
temperature, illumination, &c., the germination of the seeds 
and the subsequent growth of the seedlings during the autumn 
and the winter, that the plants should be in a position to 
throw up their shoots in the following summer. In order to 
maintain the earth in the pots, day and night, as nearly as 
possible at the temperature (22 0 C.) which I found to be most 
suitable, I made use of a large shallow water-bath, 10 cm. in 
thickness, which occupied a closed space in the small green- 
house attached to my laboratory, and was distant only 
20-25 cm. from the glass above it, being inclined so as to be 
about parallel to it. The pots were 10 cm. in diameter ; each 
either contained a single plant from the beginning, or two 
plants, the weaker of which was removed so soon as they 
began to touch each other. By a control-experiment it was 
ascertained that it would not suffice to heat the water-bath 
only during the day-time ; plants treated in this way threw 
up no shoots in the following summer. Continuous heating 
was required, and this was carried on from the middle of 
September, when the sowing took place, until the middle of 
November, at which time the seedlings had five or six pairs 
of leaves, the leaves being about 14 cm. in length. 
The experiments were begun on September 17, 1892, and 
on September 15, 1893, the seed used being in each case that 
which had just before been harvested. With the success of 
the experiments the whole life-cycle of these biennial plants 
was brought within the limits of a single year ; and it would 
