SPECIES AND VARIETIES. 



339 



kind. By scattering the pollen of one plant on the pistil of an allied 

 species, seeds are formed, which, when sown, produce intermediate 

 forms or hybrids (^[ 516). Hybrids, however, are rarely perpetuated 

 by seed. 



706. Many species vary in a remarkable manner, without any ex- 

 ternal influences to account for it. Thus, a plant of Fuchsia has pro- 

 duced, in successive years, flowers differing so much in form and 

 shape, that, if they had not been known to be produced by the same 

 plant, they would have been considered as belonging to distinct species. 

 Such is also the case with Calceolarias, some species of Amaryllis, and 

 many Orchids. Hence there is sometimes considerable difficulty in 

 determining what are true species, and what are only varieties, more 

 especially when these varieties are permanent and reproduce themselves. 

 To this must in part be attributed the disputes which have arisen among 

 botanists as to the species of many British genera, such as Roses, Rubi, 

 Salices, and Hieracia. The following table shows the number of British 

 species in some of the British genera, as given by different authors, 

 and exhibits the uncertainty which still exists as to the limits of 

 species: 



Salix. 



Hudson (1798) 16 



Smith (1824-28) 64 



Lindley (1835) 29 



Hooker (1842) 70 



Babington (1843) 57 



"Watson (1844) 38 



Babington (1847).. ..58 



707. It is only after a careful study of such forms during a series 

 of years, that any conclusion can be drawn in regard to them. It is 

 important to record all the varieties which occur, but great care is 

 necessary not to raise to the rank of species what are mere accidental 

 aberrant forms. Some have of late years advocated the doctrine of the 

 transmutation of species, or the conversion of one species into another. 

 It has been said, that Oats may be changed into Rye, by being con- 

 stantly cut down for a series of years before flowering. Such state- 

 ments are not founded on correct data, and have led to very erroneous 

 views and doctrines, which have been recently promulgated with much 

 apparent plausibility. All that has been observed in the vegetable 

 kingdom leads to the conclusion, that there are distinct species which 

 continue to be perpetuated by seed, and that, although these may vary 

 within certain limits, there is always a typical form to which the 

 varieties have a tendency to revert. By grafting and other horticultural 

 operations, changes of a marked kind may be produced in fruits; but 

 the seeds of such fruit, when sown, give rise to individuals resembling 

 the original stock they perpetuate the typical form, not the artificially- 

 produced variety. 



