140 ORIGINAL ARTICLES. 



may often be observed in great numbers for hundreds of yards along a 

 roadside, all of one sex, evidently all from suckers, originating, perhaps, 

 many years back in a single individual. In like manner, an individual 

 bramble will, in the course of years, spread through a whole wood ; a 

 fragment of coltsfoot or couch grass infest large fields ; or JSlodea Ca- 

 nadensis fill our canals, though not a single seedling be raised. 



One of the greatest difficulties in arriving at a just conclusion as to 

 the value to be attached to intermediate forms, is owing to the doubts 

 which still hang over the question of hybridity. The existence of hy- 

 brids in the vegetable kingdom, less perfect in their nature than true 

 species, analogous to the mule among animals, has at all times been a 

 popular notion ; and wild plants, having some resemblance to cultivated 

 or useful ones, but less perfect in respect of the qualities sought from 

 them, have in most countries been stigmatised as bastards. Linnseus 

 corrected many of these popular errors which had crept into the scien- 

 tific nomenclature of the day ; but he still gave his sanction to the idea 

 of the hybrid origin of certain species, by adopting the term as the spe- 

 cific name in certain cases, without, however, probably having given the 

 matter much consideration. Since his time it has been shown that his 

 Chelidonium hybridum, Vioia hybrids,, Campanula hybrida, Chenopo- 

 dium hybridum, &c, are genuine, substantive species ; and the existence 

 of hybrids in a state of nature has been denied by several botanists, and 

 admitted only with great reservations by some even of the most distin- 

 guished ones of the present day. Others, on the contrary, of our most 

 acute observers, having acquired convincing evidence of natural hybri- 

 dity in a few cases, have generalized their conclusions ; they have sup- 

 posed natural hybrids to be of constant and frequent occurrence ; and 

 they have ascribed to this cause alone the majority of variations from 

 the supposed typical forms cf species, or even attributed to original hy- 

 bridisations the multitude of nearly allied, but constant species, in seve- 

 ral of the largest genera. 



That wild hybrids do exist, I had already convincing evidence from 

 personal observation during the years 1825 and 1826, when my atten- 

 tion was specially directed to the search after them in the Pyrenees 

 and the South of France; and the proofs brought forward by other 

 observers are not to be resisted. But the cases are very few, and it re- 

 quires great caution before we can attribute to this cause the appearance 

 of individuals of a species showing some approach in their characters 

 to some other species. In Western Europe, there are but six genera 

 in which I have myself been able to collect satisfactory proofs of na- 

 tural hybrids, viz., Cistus (including Helianthemum), Geum, Saxifraga, 

 Gentiana, Verbascum, and Digitalis. We are also bound to admit on the 

 authority of other observers, at least four more, viz., Epilobium, Carduus 

 (including Cirsium), Salix, and Narcissus, and perhaps also Centaurea, 

 Erica, Rumex, and Polygonum. The supposed hybrids in Viola, Medi- 

 cago, Primula, if cross-breeds at all, are probably between varieties of 

 one species, not between two species. The cases adduced in Serapias, 

 Aceras, and Orchis, require much farther investigation, especially now 





