538 



Heritable Spiral Torsions. 



recall Dracoeeplialiiiii inoldavicuin (Fig. 74, p. 369), 

 Aspenila azurca, Centranthus macrosiphon and especially 

 Mercurialis annua. In the latter species these malforma- 

 tions appeared almost every year and often in consider- 



Fig. 126. Eqiiisetum Tehnatcja. Spiral torsion of an 



erect stem. 



able nnmbers, in my tricotylons and syncotylons races 

 (Fig. 96, p. 464). 



Unless direct experiments in isolation have been made 

 it is impossible in the majority of cases to be certain 



