Relation to Cultivation . 
419 
sequently the more vigorous the growth of the plants, the 
richer is the progeny obtained from any given seed in indi- 
viduals with twisted stems, and the more marked is the 
twisting in the individuals. 
4. The most important condition is that the plants shall 
have plenty of space for their growth : they must not over- 
shadow each other, and they should touch each other as little as 
possible. There ought never to be more than 20-25 plants 
to the square metre ; and even then the plants come into 
contact with each other in the autumn : it would be better 
not to have more than 10-15 plants per square metre. 
When too closely planted, the number of plants with 
twisted stems per square metre is less than that obtained 
with more remote planting ; so that the greater number of 
individuals is not an advantage but a disadvantage. In the 
case of close planting, the twisted individuals are confined, 
either exclusively or for the most part, to the border of 
the bed. 
5. The time of sowing is of importance, for this determines 
the length of life of the plant up to the time when the shoot is 
thrown up : the longer this period, the conditions being 
favourable, the greater is the prospect for biastreptic indi- 
viduals. 
Sowings in the summer or in the early autumn yield 
seedlings which throw up shoots in the following year, which 
shoots show little or no tendency towards biastrepsis. On 
the other hand, good results are obtained from autumn- 
sowings, yielding plants which do not throw up their shoots 
until the next summer but one, and have therefore a longer 
rosette-stage : the proportion of biastreptic plants is in this 
case rather larger, if anything, than in the case of ordinary 
spring-sowings. 
With regard to the spring-sowings, it does not appear to be 
a matter of great importance whether the seed be sown in 
March, in April, or early in May ; or whether the seed be 
sown directly in the beds, or in pans in the greenhouse, the 
seedlings being subsequently planted out. For various reasons 
