FROM a recent address of Mr. Bentham, the President of the Linnæan Society, it would appear to be still uncertain whether the weeds which appear spontaneously on ground which has been newly turned over, spring from seeds hidden in the ground, or from seeds accidentally carried on to the new surface. Could not this question be decided by a simple experiment, namely, by turning over some suitable ground and covering parts of it by gardener's glass frames, so as to prevent the importation of any seeds? So far as the weeds are the same both within and without the frames, it is certain that they must spring from seeds previously contained in the earth. It is true that there will be a difference of temperature beneath the glass and in the open air, but it would not prevent us from learning what seeds are really contained in the earth. A frame covered with fine muslin would serve instead of glass if the muslin be fine enough to prevent the passage of any seeds.