466 Syncotyloiis Races. 



In the spring of 1894 I planted out into separate beds 

 some syncotyls and amphi-syncotyls from my tricotylous 

 intermediate race of Mercnrialis annua, which produces a 

 large number of syncotyls every year. There were three 

 female plants and some male ones. Saved separately, their 

 seeds produced 4, 19 and 24% syncotyls, amongst which 

 hemi-syncotyls and amphicotyls appeared in considerable 

 numbers. There is i'lttle doubt that I would have suc- 

 ceeded in isolating the syncotylous intermediate races 

 from Mercnrialis (with 24%) as well as from Ccntran- 

 fhus (with 37%), and also perhaps from Picris (8%) 

 and ralcriana (6%); but the difficulties, due mainly to 

 the retarded growth of the plumule, have led me to limit 

 my experiments in this direction to a single species, 

 Hclianthus annuus. 



§ 10. HELIANTHUS ANNUUS SYXCOTYLEUS.i 



As early as 1887 I found a syncotylous race of the 

 ordinary sun-flower and isolated it immediately. Since 

 then I have grown this race for ten generations. It has 

 always been extremely variable, both in the extent of 

 the fusion of the cotyledons and in the percentage num- 

 ber of syncotylous seedlings. On the other hand it has 

 proved perfectly constant and immutable. 



For instance, every efifort to bring it to a uniform 

 condition, free from atavists, or, on the other hand, to 

 reduce it to the corresponding half race, has failed, in 

 spite of the most stringent selection. Therefore we have 

 here as good an instance of a constant type, which, in 

 its visible properties merges into other races, i. e., is 

 transgressively variable, as was furnished by the best 



^ Over de crfelykhcid van Synfisen. Kruidknndig Jaarboek, 1895. 

 pp. 136-142 and Plate IV. See also the same journal, 1894. 



