SEASONAL DIMORPHISM, ETC. AT 
cannot be any question of the parental species being the one, 
which we call typical A. triphyllum. For considering its mor- 
phological equipment, expressed by the characteristic struc- 
ture of its organ of vegetative reproduction, the tuberous 
rhizome, such rhizome belongs to plants inhabiting higher 
situations, where it typically grows, and not to such as occur 
in low» woods, inundated during the winter, or in bogs, 
sphagnum-bogs for instance. In the singular environment 
where the variety pussilla occurs, we have a natural explana- 
tion of the reason, why it blooms so much later than the 
typical plant. And accompanying this distinction as to time 
of flowering and fruiting we have seen the marked color of 
the spathe and spadix, the frequent variation in the leaf-out- 
line, and the slender stem. If these characters remain con- 
* stant, “pussilla’’? may eventually deserve specific rank, and we 
shall have a well founded proof of how some species may arise 
and “from more than_one single area.” For it is hardly pos- 
sible to believe that the variety pussilla, as it grows in Mary- 
land, originally came from the north, where it also occurs, or 
vice versa. It might have become distributed by means of 
the berries, but it seems much more reasonable to suppose, 
that the change of environment has produced this particular 
type, “wherever it occurs.”’ A conclusion to that effect would 
only corroborate the view advanced by Wallace: “that every 
species has come into existence coincident both in space and 
time with a pre-existing closely allied species” —with the typi- 
cal form of Arisaema triphyllum in this particular case. We 
would at the same time see no obstacle against believing that 
each species does not need to have been produced within one 
area, from where it migrated as far as it could; the origin 
cf the Euphrasiae, the Gentianae, the species Alectorolophus, 
and our variety of Arisaema seem to depend on factors, some 
of which are among those which Schouw evidently had in 
mind, when he wrote his thesis: ‘De sedibus plantarum 
“originarils”* and reached the conclusion: ‘“‘Hadem momenta 
cosmica easdem plantas diversis in locis produxise.”’ 
This hypothesis of Schouw was not new however, for it 
had actually been proposed by Gmelin in his “Sermo de 
4 Kjoebenhavn 1816. 
