84 Sudden .Ifpcarancc and Constancy. 



Catananclic cocndca alba (5), Hyssopits officinalis albus 

 (198), Lobelia syphilitica alba {537), Lychnis chalcedo- 

 nica alba (401), Polenioniuni dissectuui album (126), 

 Salz'ia syk'cstris alba (296). The following white vari- 

 eties of annual species I also found to be perfectly con- 

 stant : CJirysantheniuni covonariuni album (400), Godetia 

 amoena, white Pearl (15), Linum usitafissimum album 

 (779), Phlox Drummondi alba (50), Silene Armcria alba 

 (617). Among wild species I subjected especially Ero- 

 diuni cicutarium album, which is common in Holland, 

 to a severe test. In this form the pigment characteristic 

 of the species is lacking both in the leaves and in the 

 flowers. I found the variety constant through five gen- 

 erations in my experimental garden, not a single red 

 plant appearing although the sowings were conducted on 

 a very large scale. Later I collected seeds of the 7'ar. 

 alba from another locality and found it also to be con- 

 stant (43 specimens). 



Other color varieties usually prove equally pure if 

 the seeds of plants that have been isolated are sown. In 

 some cases this fact is so generally known that they have, 

 on this ground, been raised to the rank of species, as, 

 for instance, Anagallis (arzrnsis) cocvulea. In 1897 I 

 had 25 examples of this variety flowering on an isolated 

 spot, and from these in 1898 I had 866 plants which were 

 without exception blue. Tetragonia expansa, whose leaves 

 and flowers are normally reddish brown, has given rise 

 to a pure green form which has been raised to the rank 

 of a species under the name of T. crystallina. This I 

 also found perfectly constant. In 1898 I sowed about 

 600 fruits obtained from a culture of 1897. Each fruit 

 contains from 6 to 10 and often more seeds, which grer- 

 minate sooner or later, some of them not until after a 



