Relation to Cultivation. 
401 
means by which I obtained the hereditary breed. I was 
then in a position to report upon the first four generations 
of this biennial ; I now give the results of my observations on 
the subsequent generations. 
My breed was derived from two individuals with a twisted 
main stem, which made their appearance among plants 
obtained from a sowing in 1884. Before they flowered, all 
the other individuals had been removed. From the seed of 
these two I obtained the second generation in 1886. At 
that time I was unaware of the special conditions essential to 
the successful cultivation of these plants, and, doubtless on 
this ground mainly, I found only two twisted individuals 
among about 1650 seedlings. Both of these flowered in 
isolation, and bore seed abundantly. From this seed the 
third generation was raised in 1888-9, consisting of about the 
same number of plants, among which were sixty-seven with 
twisted stems, that is, about 4 per cent, of the total number. 
The seed-bearing plants selected were flowered in isolation. 
The seed for the fourth generation was sown, in part, in 
1890, and gave about 10 per cent, of twisted individuals, which, 
owing to an accident, could not be used for the propagation 
of the breed. The remainder of the 1888-9 seed was therefore 
sown in 1891, and, with a better knowledge of the requisite 
conditions, I obtained 34 per cent, of twisted individuals, a 
percentage which has been approximately maintained, but not 
materially exceeded, in subsequent generations. 
The improvement in the method of cultivation was essen- 
tially this, that more space was allowed to the young plants 
from the very beginning. In the two previous generations 
about fifty individuals were grown to the square metre ; in 
this generation the number was reduced to about twenty-five 
by the repeated weeding-out, during the month of June, of 
all superfluous plants so soon as they began to touch one 
another. 
The sowing on the beds was done in the middle of May, 
1891. At the beginning of October I found that about 
half a dozen plants in every hundred had spiral phyllotaxis 
