562 Heritable Spiral Torsions. 



it. For this reason I allowed ])lants with a right-hand 

 spiral only to flower in the seventh generation ; and in the 

 following one also, the spiral of all the chosen seed- 

 parents was right-handed. The result was as follows : 



LEAF-SPIRAL 

 RIGHT-HAND LEFT-HAND 



8th generation 205 215 individuals 



9th generation 40 24 individuals 



These constant but eversporting twisted varieties offer 

 fa\orable material for attempting to transfer the mal- 

 formation to related species by means of hybridization. 

 At present, however, only a single attempt of this kind 

 lias been made, viz., one which was communicated to me 

 by Prof. Le Monnier of Nancy. ^. 



He sent me two twisted stems of Dipsacus ftiUonuni 

 which exhibited a torsion as pronounced and as complete 

 as the best instances of my race (Fig. 123 a and h, p. 

 529) ; and which owed this malformation to a cross be- 

 t^veen the species in question and my Dipsacus syh'csfris 

 tarsus, which Mr. Le Monnier had cultivated on a large 

 scale for many years. 



In 1896 my race flowered at the same time as the 

 normal D. fuUonnui in the botanical garden at Nancy, 

 at a distance of 100 meters apart but in great quantities 

 of individuals. Pollen could easily be transferred by 

 insects from one bed to the other. From the seeds of 

 these Dipsacus fuUonuui there arose besides numerous 

 normal plants three with twisted stems; one of them 

 had upwardly directed bracts in the involucre, a char- 

 acter of D. syh'csfris which distinguishes it from D. ful- 

 louuui. The investigation of this important question has, 

 however, not been continued. 



' Jniini. Roy. JJorfic. Soc, 1900, Vol. XXIV, p. 69. 



