404 De Vries . — On Biastrepsis in its 
At the end of May, 1898, I found that these consisted of— 
Plants with twisted stems 32 = 46% 
,, £ phyllotaxis 21 = 30% 
„ normal decussate 17 = 24% 
Total 70 
The proportion of stems in which the twist was to the left 
or to the right respectively was maintained unaltered in this 
generation, there being usually about an equal number of the 
two kinds, as shown in the following table : — 
3rd generation, 1889 
29 right 
27 left 
4th 
1892 
21 >> 
33 
>> 
7* 
1898 
H » 
17 
yy 
The whole history 
of the breed may be 
summarized in 
a tabular form as follows : — 
Generation. 
Sowing. 
No. of 
No. to 
Percentage of 
plants. 
square metre. 
twisted stems. 
1. 1884-5 
Bed 
— 
— 
— 
2. 1886-7 
>> 
1643 
— 
0*1 
3. 1888-9 
y y 
1616 
35 
4 
4. 1891-2 
„ May 15 
107 
2 5 
34 
5- >893-4 
House, Mar. 17 45 
22 
10-20 
6. 1895-6 
„ Mar. 11 33 
8 
42 
7. 1897-8 
„ May 5 
70 
16 
46 
Whilst at first a large number of plants, crowded 
together, were used with imperfect success, in the later years 
fewer plants with plenty of space have afforded much more 
satisfactory results. This improvement is due in part to the 
more favourable cultural methods, in part to the continuous 
selection ; it is impossible in this case, as usually in other such 
cases, to discriminate between the effects due to these two 
causes respectively. It will, however, be shown in the next 
section that the better cultural methods were of considerable 
importance in bringing about the result. 
B. The Influence of Space. 
The condition most essential to the successful cultivation of 
these twisted plants is that each plant shall have sufficient 
room in which to develop freely ; the plants must neither 
