366 © BOTANICAL GAZETTE [NOVEMBER 
Completion of the cycle 
The individual which began with the germination of the seed 
and the organization of the stem apex in the sheath at the base of 
the cotyledon, has been followed through the series of changes 
normal to its development as Erythronium americanum, and the 
variations have been indicated between this species and the others 
of the genus. The cycle of the sporophytic generation is thus 
completed, and the original stem apex culminates in the formation 
of the flower parts of the first blossom produced by the bulb on 
reaching maturity. It was shown that the species were structurally 
related with a large group, the western species, behaving similarly, 
the others diverging more or less from the habits of these forms. 
The structures involved in the divergence from type are those 
most active in the immature stages, and most freely produced in 
E. americanum. This species, therefore, has been regarded here 
as the most remote from the ancestral form, since the majority 
of the species are of the more simple type of development in the 
vegetative habits. The species having the uniform vegetative 
habits are native to the region from the Rocky Mountains west- 
ward, becoming more abundant in species as the Pacific coast is 
approached, and culminating in a series of habitats in southwestern 
Oregon. This may be assumed to be near the original home of 
the genus, from which the distribution and differentiation into 
the present habitats and species have occurred. It is probable 
that the lines of migration have followed the present lines of 
specific distribution, especially in the United States. The single 
species of Eurasia combines the bulb characters of the western 
species with the withering aerial parts of the eastern forms. The 
character of the habitats in which this species occurs may be so 
nearly uniform that no marked variations have been developed from 
the original type, beyond that involved in the prostrate fruit. a 
have been observed carrying the seeds of E. americanum, and it 1s 
probable that they aid in distribution in each of the species having 
seeds with fleshy raphe or spur tissue. This would include E. Dens- 
canis as one of the myrmechochorous species, as a considerable 
chalazal spur is present, comparable to that of Viola or Sanguinaria 
(BEAL 1), but not so large as that of E. americanum or E. albidum. 
