spirally Tzvistcd Races. 549 



of 16 individuals per square meter. Altogether there 

 were 70 plants. 



A record made at the end of May 1898 gave the fol- 

 lowing result: 



Twisted stems . . . . 32 =46% 

 Ternary stems . . . . 21 =30% 

 Decussate stems . . . . 17 =24% 



Total 70 



In the eighth generation the plants were treated in 

 exactly the same way as in the preceding one. As already 

 mentioned, the offspring of 10 distinct parents were 

 compared. Moreover for each parent the seeds of the 

 terminal inflorescence were compared with those of the 

 inflorescences on the main branches. For the latter de- 

 termination I selected from each parent 4-8 of the strong- 

 est branches which arose from that part of the middle 

 of the stem which had undergone most torsion. They 

 corresponded, therefore, with the period of maximum 

 activity of the stem,^ and confirmed this by the fact that 

 small local torsions appeared on them. From the seed of 

 the primary inflorescences I raised 645 plants with 31%, 

 from those of the secondary inflorescences 650 individ- 

 uals with 34% cwisted main stems. There was therefore 

 no difference of any significance. 



The ninth generation was composed partly of off- 

 spring of twisted individuals and partly of those of ata- 

 vists. The method of culture employed was the same as 

 before; but I shall revert to the result of it in the next 

 section. 



Besides Dipsacns sylvcstris I have grown two (^ther con- 

 stant races with an abundance of fine torsions which must 



*See T. Tammes, Die rcnodicitat morphologischcr lirschci- 

 nungcn hci den P fiance n, Kon. Akad. v. Wet., Amsterdam, 1903. 



