That plants may be propagated for long periods by buds, without the aid of sexual generation, we may safely infer from this being the case with many plants which must have long survived in a state of nature. As I have had occasion before to allude to this subject, I will here give such cases as I have collected. Many alpine plants ascend mountains beyond the height at which they can produce seed. (18/110. Wahlenberg specifies eight species in this state on the Lapland Alps: see Appendix to Linnaeus 'Tour in Lapland' translated by Sir J.E. Smith volume 2 pages 274-280.) Certain species of Poa and Festuca, when growing on mountain-pastures, propagate themselves, as I hear from Mr. Bentham, almost exclusively by bulblets. Kalm gives a more curious instance (18/111. 'Travels in North America' English translation volume 3 page 175.) of several American trees, which grow so plentifully in marshes or in thick woods, that they are certainly well adapted for these stations, yet scarcely ever produce seeds; but when accidentally growing on the outside of the marsh or wood, are loaded with seed. The common ivy is found in Northern Sweden and Russia, but flowers and fruits only in the southern provinces. The Acorus calamus extends over a large portion of the globe, but so rarely perfects fruit that this has been seen only by a few botanists; according to Caspary, all its pollen-grains are in a worthless condition. (18/112. With respect to the ivy and Acorus see Dr. Broomfield in the 'Phytologist' volume 3 page 376. Also Lindley and Vaucher on the Acorus and see Caspary as below.) The Hypericum calycinum, which propagates itself so freely in our shrubberies by rhizomes, and is naturalised in Ireland, blossoms profusely, but rarely sets any seed, and this only during certain years; nor did it set any when fertilised in my garden by pollen from plants growing at a distance. The Lysimachia nummularia, which is furnished with long runners, so seldom produces seed-capsules, that Prof. Decaisne (18/113. 'Annal. des Sc. Nat.' 3rd series Zool. tome 4 page 280. Prof. Decaisne refers also to analogous cases with mosses and lichens near Paris.), who has especially attended to this plant, has never seen it in fruit. The Carex rigida often fails to perfect its seed in Scotland, Lapland, Greenland, Germany, and New Hampshire in the United States. (18/114. Mr. Tuckermann in Silliman's 'American Journal of Science' volume 65 page 1.) The periwinkle (Vinca minor), which spreads largely by runners, is said scarcely ever to produce fruit in England (18/115. Sir J.E. Smith 'English Flora' volume 1 page 339.); but this plant requires insect-aid for its fertilisation, and the proper insects may be absent or rare. The Jussiaea grandiflora has become naturalised in Southern France, and has spread by its rhizomes so extensively as to impede the navigation of the waters, but never produces fertile seed. (18/116. G.