Spirally Twisted Races. 543 
malformations, as soon as the culture was given sufficient 
room, nothing but small local twistings occurred in this 
case, in spite of highly favorable conditions of growth. 
From this I concluded that an eversporting variety anal- 
ogous to my Dipsacus syk'cstris torsus cannot be raised 
from these seeds. 
20. SPIRALLY TWISTED RACES. 
The often mentioned race of Dipsacus sylrestris tor- 
sus (Figs. 123-125, pp. 529-534, and Plate VI) has now 
completed its ninth generation. It consists of about 40' , 
of individuals with fine torsions and about 60% of ata- 
vists with, as a rule, decussate, but occasionally ternary, 
arrangement of the leaves. The acavists and the twisted 
plants with incomplete or interrupted spirals have always 
been destroyed before flowering. The completely twisted 
individuals, however, were left to be, fertilized by one 
another through the agency of insects. 
This I'cry stringent process of selection has had the 
result of maintaining the race at a fairl\ constant level. 
During the first two generations I did not know the proper 
conditions and sowed the seed much too thick, and con- 
sequently only obtained twisted individuals at the edges 
of the beds, and even here in small numbers. But with 
the improvement of these conditions the proportion of 
twisted stems at once mounted to 34%, and the heredi- 
tary value has since remained about the same, although 
subject to fluctuation due to the greater or less favorable 
climatic conditions obtaining in successive years. But 
no advance could be discovered. 
In order to exhibit graphically the result of this cul- 
