6 VARIATION IN ASTER 
merged into one species, and that itself shows such variants toward 
A. multiflorus and A. ericoides that all would be found connected. 
Next, the following group, Gray's Vulgares, including A. panicu- 
latus, A. longifolius and A. INovi-Belgii, would prove impossible 
to separate. In other words, the variants preserved in my own 
herbarium link together all of the fourteen northeastern species 
recognized by Gray as forming those groups, and if connecting 
links were to invalidate species, would lead to such an absurdity as 
the reduction of the whole fourteen to one, including such diverse 
extremes as A. ericoides and A. INovi- Belgii. Nor would it end 
there, for further variants would be found when looked for, leading 
to A. foliaceus, A. puniceus, and other species. Similarly among 
the broad-leaved species, a chain of variant links connects together 
all of Gray's Heterophylli, and even his Patentes and Brachyphyllt. 
A third group without definite natural demarcations is afforded by 
the species now to be treated, the Bzotran series. 
Intermediate forms ought to be expected between species of 
Aster, because belonging to a youthful race. Aster being appa- 
rently of recent origin considered geologically, it is natural that 
it should present, as it does, these characteristics of a young and 
vigorous race : ; 
(a) Innate variability, or a strong tendency to vary independent 
of apparent assignable cause. 
(P) Responsive variability, or a strong tendency, in addition, to 
vary in consequence of assignable cause ; 7. e., great adaptiveness 
to environment; asters varying very promptly in response to 
change of nutrition, soil, sunshine, shade, or contiguity of associ- 
ated plants. 
As the result, a multitude of transitional forms are developed, 
species are difficult to limit, and there is opportunity for unusually 
wide divergence of opinion as to the position of the arbitrary spe- 
cific lines which must be drawn. 
Because apparently still occupying their region of original distri- 
bution, our asters of the northeastern United States may be ex- 
pected to be prolific in intermediate forms. Like the Red Oak 
section of Quercus, like Lechea, like Solidago, like Viola, Aster is 
a genus in which multitudinous variants occur, which might have 
been exterminated had great alterations in climate or geographical 
