Cockayne. — The Terms "Species " and "Variety " in Botany. 77 



species segregated by Jordan from Draba verna L. (Erophila verna E. Meyer) 

 in his classical experiments. The true biological species are, in fact, the 

 microspecies, whereas the aggregates are merely collections of these and 

 may be termed " taxonomic species." Included with the biological species 

 are the supposed true-breeding species, on the supposition either that 

 these were once parts of aggregates, or that they are true-breeding entities 

 which have originated from some earlier species by a change of great magni- 

 tude,* but are none the less biotypes. To the gardener and farmer, both of 

 whom are deeply concerned with species, it is only the microspecies (biotypes) 

 and the supposed invariable species, no matter their origin, which are 

 of any moment. f And these alone answer the conception of a species 

 as a true-breeding entity of both the pre-Darwinian and post-Darwinian 

 biologists. 



The paramount importance of varietal names stands out clearly enough. 

 As noted early on in this paper, in all the floras of New Zealand up to the 

 present time an aggregate species, if it has been split up at all, has usually 

 been treated in two distinct ways. In the one case the specific name has 

 been applied to one distinct variety, the so-called species ; but in the other 

 case each variety has been accorded a distinct name, and the specific 

 name applied to the varieties taken together. In the latter case there 

 is really a trinomial nomenclature, the species being but an idea. Moss 

 has adopted the latter method in his Cambridge British Flora, and it seems 

 to me the only biologically sound procedure. By the believer in species 

 having originated through small changes each of the invariable species 

 should be accorded, in addition to its specific name, a varietal name, since 

 each is, in his opinion, the surviving variety of a former aggregate ; but 

 in practice this does not seem necessary, or even advisable. On the 

 other hand, in the case of aggregates each, variety, including the " type," 

 should receive a distinguishing name. Of course, this procedure would 

 lead to many new varietal names being given ; but it would, of neces- 

 sity, take place by slow degrees, while its value for extending a real 



* Lotsy is of opinion, according to his highly suggestive theory of the origin of 

 species by crossing (Proc. Linn. Soc., p. 73 et seq., 1914), that changes may be of extra- 

 ordinary size. " So," he writes, " the introduction of the unknown factor x may have 

 caused in some invertebrate the formation of the skeleton, and, if this is true, it is hopeless 

 to look for a transition between an invertebrate and a vertebrate, as none such ever 

 existed " (I.e., p. 84). 



A recent paper by C. S. Hoar (Sterility as the Result of Hybridization and the 

 Condition of the Pollen in Rubus, Bot. Gaz., vol. 62, pp. 370-88, 1916) gives various 

 examples of more or less fertile interspecific hybrids. He points out how Linnaeus 

 considered various hybrids good species, using hybrida for the specific name. The case 

 of Viola, investigated by Brainerd, is also cited, where hybrids made between closely 

 related but distinct species with characters intermediate between unlike characters of 

 the present forms bred true from generation to generation (Hybridization in the Genus 

 Viola, Rhodora, vol. 8, pp. 6 and 49, 1906). 



Willis, as the result of studies in the distribution of the Ceylon flora, based on the 

 comparative frequency of species (Phil. Trans. Roy. Soc, ser. B, vol. 206, p. 307 et seq., 

 1915), considers that all species arise by mutation, and that the new character may be 

 either small or of great size. This botanist does not believe in the killing-out of inter- 

 mediate forms (I.e., p. 330). 



t Horticultural and agricultural common-sense is far in advance of taxonomic 

 science, as evidenced by the gardener and farmer having definite names for their innumer- 

 able varieties of ornamental plants, vegetables, and cereals. A binomial or even a 

 trinomial nomenclature is of little use in actual horticultural or agricultural practice. 



