In 1845, a violent tornado swept a wide strip of forest in Northern New York, from the more thickly settled portions of Jefferson County to Lake Champlain. The timber that succumbed to the force of the tornado, and growing at various points along its track, was mainly beech, maple, birch, ash, hemlock, spruce, etc.; but it was rarely replaced, at any point, by the same timber, in the growths that almost immediately followed. The trees that are now growing along the track of the tornado are principally poplar, cherry, birch, and a little beech and ironwood: no ash, maple, spruce, or hemlock, except here and there, at considerable intervals, a tree or two which may have been replaced by natural seed. The important fact noticeable, in this connection, is that the aggressive timber--that replacing the old--entirely usurped the place of the evergreen growths, supplanting them with those that were wholly deciduous. Besides, it does not appear that the poplar, the cherry, and the ironwood, which were altogether aggressive, previously grew near enough to the track of the tornado to have possibly supplied the seed necessary for their appearance and growth. The fact was specially noticeable at the time, and has been widely communicated since, that the white oak timber cut off at Valley Forge for fuel and other army purposes in the American camp, in the winter of 1777-78, was succeeded by black oak, hickory, chestnut, etc.--the white oak entirely disappearing, although by far the most favorably situated for propagation by seed. But the alternations of forest growths had attracted too little attention at that time to render the meagre facts given of any special value to scientific men. If the usurping timber had grown in the immediate neighborhood (a fact not stated), it might have come from natural seeds, and not from primordial germs under "favoring conditions." In the Ohio Agricultural Report of 1872, an account is given of a storm-track, in that state, which swept for a considerable distance, and was violent enough to bear down all the timber before it. It is stated that the path of this tornado (which must have occurred many years ago) "had grown up with black-walnut, another and different growth from that prostrated by the force of the storm." In this instance, there were no neighboring trees, except perhaps at distant intervals, from which the nuts of the black-walnut could have been derived, unless they had been promiscuously strewn by the tornado along its entire track. But it is, unfortunately, not stated that the tornado occurred at that opportune season of the year when the nuts were properly matured for planting.