A year ago last autumn, while rambling about the fields, we took especial notice of the galls upon the golden-rod. We saw that there were two kinds, the elongated and the round. We knew that from the former came a tiny moth, well-known to us, and from the latter a fly with which we were not familiar, or, if familiar, not known to come from this gall. The elongated galls were all empty, but the round ones we found upon examination contained each a small white grub. We gathered a quantity of the galls and placed them in a jelly glass on the writing table where they would be constantly before us for observation.