Three years ago I published my observations on the succession of forest growths in the Rocky Mountains and all the forests in the Northwest. Since that time it has been observed that the same rule applies to Europe. In the Gardeners' Monthly for July an article on the same subject copied from the Independent and headed " Succession of Forest Growths," names the very same trees that I referred to, but in a way which shows that the writer did not understand my meaning. He says, "In the Rocky Mountains of Colorado the first tree to take possession of the rocky heights is the Aspen Poplar. No other tree attempts to take possession of the sterile sod".

Now my observations have extended over many years, and long journeys in the mountains, yet I fail to bring to mind a single instance where the aspen has taken possession of the sterile soil on the rocky heights, except where the land had previously been burned over; and where the land had been burned over, it is proof positive that timber had already grown there; so this does not prove that it was the first tree to take possession.

The natural place for the aspen is in moist soil, and there it will be found making its best growth. It was an interesting fact for me to notice that this tree, or its seeds rather, are so delicate that they will not germinate even on land slides, but newly burned land is in the best condition possible for delicate seeds; and this tree has a better opportunity than any other I know of for reaching the burned land. Its seeds ripen in spring; they are produced in incalculable numbers, and so small that a million would not weigh a pound; they are floated in the air on wings of down, so that they are the only seeds which can reach the mountain tops, but they cannot germinate so well on ordinary dry land as many other trees; and undoubtedly if the seeds of pines could reach the sterile soils and rocky heights, they would be more at home than the aspen.

The writer, still speaking of the aspen, says: "No sooner, however, does it spread over the wide acres, than the twisted pine (Pinus contorta) rushes in, contests the ground, and finally conquers".

Now, in what way can the Pinus contorta "rush in" on these rocky heights of sterile soil ? Its seeds are not light like the seeds of the aspen. They could not cross the valleys from another mountain, and the trees, each one of them must have a seed to start from. In cases where Pinus contorta " rushes in" as soon as the aspen has spread over the wide acres, it will be found that it started from the seeds at the same time the aspen did, but in four years it would not be so tall as the aspen grew the first season.

Pinus contorta (it is now called Murryana) has very persistent cones. I have seen trees that have held their cones sixteen years, very many if not all of them still enclosing the seeds. Heat is the best and almost the only instrument that will open these cones; hence when a fire destroys the forest many of these seeds are just in the right condition to germinate, and they can be seen springing up in countless thousands, and by counting their annual growths in the older burnings, you may tell quite accurately in many instances, the year when the forest was burned.

It is quite possible that the aspen may antedate all others of our forest trees, indeed it has been found imbedded in the fens in Northern Europe, deeper than almost any others of our commonest forest trees, but this is no reason why we should jump to the conclusion that its growing on the Rocky Mountains at high elevations proves it. It only grows on burned lands and on moist places, and its seeds give it that advantage.

I do not see a particle of evidence in any of the mountains and forests, to prove that there is a succession of forest growths at all, except where the lands have been burned over, or where the conditions have been changed by being flooded, or by being changed by some convulsion of nature; and these instances are so rare as hardly to need a passing notice. The writer goes on to quote Hansen's observations on the same subject, but in this case also he neglects to state that the aspen is the first tree to appear on burnt lands, and the birch the next, just as I reported of the burnt lands in Northern Wisconsin, and the Black Hills of Dakota. It seems to me that any man who will take time to look into this matter will see plainly that the birch must follow the aspen, and see just as plainly that it must drive the aspen out for it too produces immense quantities of fine light seeds. It.does not require a very large birch tree to produce two or three million seeds in a single season. Now although the birch did not have an even start with the aspen, it has a very great advantage over it after it once gets established; as the aspen is a short-lived tree, and does not reach a great height, the birch soon overshadows it.

And add to this that the aspen seeds will only germinate on finely pulverized soil or on moist land, it will be seen that it must confine itself to the margins of streams, or to moist lands - as it does - to abide its time, till another forest fire gives it an opportunity to extend its bounds. Now what evidence have we of the succession of forest growths, where the timber has been cut off without fires having run over the land ? In New England pines are fast covering the lands where pines originally grew. And as a general thing, this is so all over the country, except in some parts of the country where the land is very sandy, and having become broken and washed by heavy rains, the sands have been blown around in a few localities without having been burned over; and in dry climates like Colorado, where, when the forests have been burned off, and the land exposed to the parching sun and drying winds, there is no probability that the land will ever produce vegeta-t'.on of any kind for ages to come.

Indeed it is only at the highest altitudes that Pinus Murryana is to be met with, and where there is more moisture than nearer the base of the mountains.

Waukegan, III.