The Elements of the Species. 59 



which grow in New Zealand, have been raised by Cun- 

 ningham into 7 well-defined species ; but since con- 

 necting links between all these seven forms are found in 

 different countries Hooker has united them into a single 

 species.^ 



Another good example is furnished by Loiuaria pro- 

 cera, a fern from New Zealand, Australia, South Africa 

 and South America. If we were acquainted with the 

 forms from one of these localities only, we should recog- 

 nize, in them, a number of species. But when those from 

 all these localities are compared they form a complete 

 series, and they are consequently united as a single spe- 

 cies. But this species comprises a much larger series 

 of forms than all the remaining species of Lomaria put 

 together. 



The limits of collective species arise therefore by the 

 dropping out of links in the chain of elementary species. 

 These gaps are apparent when one confines his attention 

 to a single region; and real if they still persist when the 

 Floras of the world have been examined. If the O.valis 

 corniculata or the Loiuaria procera ceased to exist in any 

 one country the present species would have to be split 

 up into smaller ones. 



Or in other words : Linnean species arise by the dis- 

 appearance of single elementary species from a hitherto 

 unbroken series. This origin is therefore a purely his- 

 torical occurrence and can never become the object of ex- 

 perimental investigation.^ 



^'Species" therefore have very little physiological sig- 



* J. D. Hooker, Introductory Essay to the Flora of N'e^i' Zealand, 

 1853, p. 18. Compare also Hooker's account of Aconitum Napellus. 



^ The famous expression of Spencer, The survival of the fittest, 

 is therefore incomplete and should run the survival of the fittest 

 species. 



