THE MUTATION THEORY 349 
in the narrower sense of the word, as previously given. The second 
and third heads indicate the real progressive elementary species, first 
those which are as strong as the parent-species, and secondly a group 
of weaker types, apparently not destined to be successful. Under 
the fourth head I shall include some inconstant forms, and under 
the last head those that are organically incomplete. 
Of varieties with a negative attribute, or real retrograde varieties, 
I have found three, all of them in a flowering condition in the field. 
I have given them the names of Jaevifolia, brevistylis and nannella. 
The Jaevifolia, or smooth-leaved variety, was one of the very first 
deviating types found in the original field. This was in the summer 
of 1887, seventeen years ago. It formed a little group of plants grow- 
ing at some distance from the main body, in the same field. I found 
some rosettes and some flowering stems and sowed some seed in the 
fall. The variety has been quite constant in the field, neither increas- 
ing in number of individual plants nor changing its place, though now 
closely surrounded by other lamarckianas. In my garden it has 
proved to be constant from seed, never reverting to the original 
lamarckiana, provided intercrossing was excluded. 
It is chiefly distinguished from Lamarck’s evening-primrose by its 
smooth leaves, as the name indicates. The leaves of the original 
form show numerous sinuosities in their blades, not at the edge, but 
anywhere between the veins. The blade shows numbers of convexi- 
ties on either surface, the whole surface being undulated in this 
manner; it lacks also the brightness of the ordinary evening-primrose 
or Oenothera biennis. 
These undulations are lacking or at least very rare on the leaves 
of the new Jaevifolia. Ordinarily they are wholly wanting, but at 
times single leaves with slight manifestations of this character may 
make their appearance. They warn us that the capacity for such 
sinuosities is not wholly lost, but only lies dormant in the new variety. 
It is reduced to a latent state, exactly as are the apparently lost 
characters of so many ordinary horticultural varieties. 
Lacking the undulations, the Jaevifolic-leaves are smooth and 
bright. They are a little narrower and more slender than those of 
the lamarckiana. The convexities and concavities of leaves are a 
useful character in dry seasons, but during wet summers, such as those 
of the last few years, they must be considered as very harmful, as they 
retain some of the water which falls on the plants, prolonging the 
action of the water on the leaves. This is considered by some writers 
