Spirally Twisted Races. 547 
Twisted stems 37 =34% 
Stems with ternary whorls J2 = 11% 
Atavists with decussate arrangement of eaves 58 =55% 
Total 107 
It is very important to notice that the number of 
twisted stems increased as the result of the greater dis- 
tances between the plants, not only relatively (i e., per 
100 individuals), but absolutely (i. e., per square meter). 
In the third generation there were 50 plants per square 
meter, of which 4% (1-7%, from 1-4 specimens) were 
spirally twisted. In the fourth generation, however, 
there were 37 twisted individuals on 4 square meters or 
9 per square meter. 
I selected the seven plants with the finest torsions 
on this bed as seed-parents. They all, moreover, pre- 
sented local torsions on several branches. I isolated 
them before they flowered. 
The fifth generation (1893-1894) was not so success- 
ful. Only 25% with twisted stems were produced. The 
seed to produce this generation had not as hitherto been 
so\vn on the beds but in seed-pans in the greenhouse 
attached to my laboratory. This method has since proved 
more convenient and safer, and has been employed in the 
two generations which follow. 
The seed saved in September 1892 was sown in the 
middle of March 1893. In the middle of May the best 
seedlings were planted separately in 10 centimeter pots 
with good, richly manured garden soil, and planted in 
the bed in the middle of May, at the same distance apart 
as were the plants in the preceding generation (22 plants 
per square meter). In the following year (1894), all 
the stems developed and were recorded. The result was 
as follows : 
