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Today I have only to show that the mutations of the evening-primroses, though sudden, comply with the demands made by Darwin as to the form of variability which is to be accepted as the cause of evolution and as the origin of species. Some of my new types are stouter and others weaker than their parents, as shown by gigas and albida. Some have broader leaves and some narrower, lata and oblonga.
The indignant exile, journeying so boldly to confront the peril of which he had no suspicion or forewarning, belonged to a species confined to the forests of New Brunswick and Nova Scotia or the neighbourhood of their boundaries. He was a giant cousin of the common wildcat, and known to the few naturalists who had succeeded in differentiating and classifying his species as Lynx Gigas.
They obey the same general laws, become active under similar conditions, some of them being more easily awakened than others. The germs of the oblonga, lata and nanella are especially irritable, and are ready to spring into activity at the least summons, while those of gigas, rubrinervis and scintillans are far more difficult to arouse.
The range of the moose in North America extends from Nova Scotia in the extreme east, throughout Canada and certain of the Northern United States, to the limits of tree growth in the west and north of Alaska. Throughout this vast extent of territory but two species are recognized, the common moose, Alces americanus, and the Alaska moose, Alces gigas, of the Kenai Peninsula.
They must have been of various sizes, some no larger than a small sand-piper, while others, judging from their footprints, which measure no less than nineteen inches, must have been twice the size of the modern African ostrich. The distances between the smaller measure only about three inches, but in the base of the largest, called the Ornithichnites Gigas, they are from four to six feet apart.
Darwin found one of the species the Trochilus forficatus flying about amid the snow-storms in the forests of Tierra del Fuego; while in the wooded island of Chiloe, which has an extremely humid climate, he saw it skipping from side to side amid the dripping foliage. In the same island is found another species, the Trochilus gigas a very large bird for so delicate a family.
If there had been any visible preparation towards the coming mutation, it could not have escaped observation. Moreover, if visible preparation were the rule, it could hardly go on at the same time and in the same individuals in five or six diverging directions, producing from one parent, gigas and nanella, lata and rubrinervis, oblonga and albida and even scintillans.
The leaves of O. gigas are broader, of a deeper green, the blade more sharply set off against the stalk, all the rosettes becoming stout and crowded with leaves. Those of O. rubrinervis on the contrary are thin, of a paler green and with a silvery white surface; the blades are elliptic, often being only 2 cm. or less in width. They are acute at the apex and gradually narrowed into the petiole.
It occurs in the OEnothera mutant gigas. The origin of it has not been clearly made out, but it must result either from the splitting of each chromosome or from the omission of the chromosome reduction.
On the other hand, gigas and rubrinervis, oblonga and albida obviously bear the characters of progressive elementary species. They are not differentiated from lamarckiana by one or two main features. They diverge from it in nearly all organs, and in all in a definite though small degree.
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