1. _Veronica spuria_, described in Amœnitates Acad. vol. III. p. 35, came from the impregnation of _Veronic maratima_ by _Verbena officinalis_; it is easily propagated by cuttings, and agrees perfectly with its mother in fructification, and with its father in leaves. 2. _Delphinium hybridum_, sprung up in a part of the garden where _Delphinium clatum_ and _Aconitum Napellus_ grew together; it resembles its mother as much in its internal parts, that is, in fructification as it does its father (the _Aconitum_) in outward structure, or leaves; and, owing its origin to plants so nearly allied to each other, it propagates itself by seed; some of which I now send with this Dissertation. 3. _Hieracium Taraxici_, gathered in 1753 upon our mountains by Dr. Solander, in its thick, brown, woolly calyx; in its stem being hairy towards the top, and in its bracteæ, as well as in every part of its fructification, resembles so perfectly its mother, _Hieracium alpinum_, that an inexperienced person might mistake one for the other; but in the smoothness of its leaves, in their indentations and whole structure, it so manifestly agrees with its father, _Leontodon Taraxacum_ (Dandelion), that there can be no doubt of its origin. 4. _Tragopogon hybridum_ attracted my notice the autumn before last, in a part of the garden where I had planted _Tragopogon pratense_, and _Tragopogon porrifolium_; but winter coming on, destroyed its seeds. Last year, while the _Tragopogon pratense_ was in flower I rubbed off its pollen early in the morning, and about eight o’clock sprinkled its stigmata with some pollen of the _Tragopogon porrifolium_, marking the calyces by tying a thread round them. I afterwards gathered the seeds when ripe, and sowed them that autumn in another place; they grew, and produced this year, 1759, purple flowers yellow at the base, seeds of which I now send. I doubt whether any experiment demonstrates the generation of plants more certainly than this.