ON HYBRIDIZATION AMONGST VEGETABLES. 



15 



rally these mules become impregnated by the pollen of Crinum 

 Capense, of which a great bed stands near them, and the offspring 

 being two-thirds Capense, revert nearly to its aspect ; but the 

 plant above mentioned did not revert, but exhibits an improved 

 form of the mule, and is in fact a new fertile species. The 

 freedom with which species of Crinum of the old Linnaean sec- 

 tion and most of the section I added thereto interbreed, furnishes 

 decisive proof that the facility of intermixture is not confined to 

 genera in which species have been rashly formed out of seminal 

 varieties, but is found when the species were even erroneously 

 considered to be of different genera. There is every reason to 

 believe that Thuja and Cupressus have bred together, and those 

 who look to the small difference between them will become satis- 

 fied that they form two sections of one genus. Sinningia has 

 been crossed with Gloxinia, and the produce is capable of being 

 crossed again. They are indubitably of one genus or original 

 kind ; and perhaps not they only, but Gesnera also and Achi- 

 menes. When we look to the botanical characters, the cha- 

 racters of very many genera, of which all the species are not 

 generally cultivated, are frequently false as to matter of fact, 

 because opportunities have not occurred, or have not been care- 

 fully used, of comparing all the species in a live state, and in 

 dry specimens the truth cannot be always ascertained. 



Therefore, if it be admitted, that there is little probability of 

 obtaining a cross between two plants generically distinct, it does 

 not follow that it would be needless to attempt an intermixture 

 between all that bear and have long borne different generic 

 names. Some observations on the inaccuracy of the views of 

 Martius and De Candolle concerning the Gesneracese, as stated 

 in the Bot. Reg. 1845, 3, will illustrate my meaning. The 

 question arose in that article, whether the subject was to be 

 called Gloxinia or Gesnera tubiflora. I have premised that the 

 separation of Sinningia from Gloxinia has been disproved by the 

 crossed produce, which even bears seed. First, then, as to Ges- 

 neria or Gesnera, the alternative of " five protuberances at the 

 base of the corolla or an equal swelling all round," is no generic 

 distinction, if the swelling of the base is to furnish such a dis- 

 tinction compared with a protuberance on one side. These pro- 

 tuberances depend in part upon the relative posture and incli- 

 nation of the calyx and tube. They are so various in different 

 species, that Achimenes patens has a long spur projecting from 

 the prominence of the base. A like objection applies to the 

 definition, " two or five glands round the ovary," which shows 

 that the thing set forth, as the fixed and determining character, 

 is a varying feature. Proceeding to the definition of Gloxinia, 

 we find, 1. calyx equal, as distinguishing it from Gesnera, with 



