Nor seem these two types to exhaust the range of variability of _Oenothera cruciata_. Dr. B.L. Robinson of Cambridge, Mass., had the kindness to send me seeds from another locality in the same region. The seeds were collected in New Hampshire and in my garden produced a true and constant _cruciata_, but with quite different secondary characters from both the aforesaid varieties. The stems and flower-spikes and even the whole foliage were much more slender, and the calyx-tubes of the flowers were noticeably more elongated. It seems not improbable that _Oenothera cruciata_ includes a group of lesser unities, and may prove to comprise a [591] swarm of elementary species, while the original strain might even now be still in a condition of mutability. A close scrutiny in the native region is likely to reveal many unexpected features. A very interesting novelty has already been described in a former lecture. It is the _Xanthium wootoni_, discovered in the region about Las Vegas, New Mexico, by T.D.A. Cockerell. It is similar in all respects to _X. commune_, but the burrs are more slender and the prickles much less numerous, and mostly stouter at their base. It grows in the same localities as the _X. commune_, and is not recorded to occur elsewhere. Whether it is an old variety or a recent mutation it is of course impossible to decide. In a culture made in my garden from the seed sent me by Mr. Cockerell, I observed (1903) that both forms had a subvariety with brownish foliage, and, besides this, one of a pure green. Possibly this species, too, is still in a mutable condition. Perhaps the same may be asserted concerning the beautiful shrub, _Hibiscus Moscheutos_, observed in quite a number of divergent types by John W. Harshberger. They grew in a small meadow at Seaside Park, New Jersey, in a locality which had been undisturbed for years. They differed from each other in nearly all the [592] organs, in size, in the diameter of the stems, which were woody in some and more fleshy in others, in the shape of the foliage and in the flowers. More than twenty types could be distinguished and seeds were saved from a number of them, in order to ascertain whether they are constant, or whether perhaps a main stem in a mutating condition might be found among them. If this should prove to be the case, the relations between the observed forms would probably be analogous to those between the _O. lamarckiana_ and its derivatives.