CHAPTER VIII. 



ON SUB8PECIFIC FORMS. 



It is a very remarkable fact, one not very creditable to the intelligence of ornithologists, 

 that a chapter on the importance of a due recognition of the existence of imperfectly 

 segregated species should be necessary at the present time. Nearly thirty years have 

 elapsed since Darwin and Wallace laid before scientific men such an array of facts to prove 

 the truth of the theory of Evolution that every student of Biology accessible to reason has 

 adopted it. Nevertheless most ornithologists still speak and write of species on the old 

 lines, and whilst admitting the truth of Darwin's theory of Evolution, ignore its existence 

 as a working hypothesis. 



It cannot be too strongly impressed upon ornithologists that if the theory of Evolution 

 be true there must always be, at any one moment in the history of birds, a number of 

 species in the process of disintegration. There may be differences of opinion as to the 

 name by which they should be called, or the best way of recognizing them in ornithological 

 nomenclature, but there cannot be any difference of opinion as to the necessity of giving 

 due importance to the fact of their existence. We may call them subspecies, conspecies, 

 morphological species, inosculating species, intergrading species, imperfectly segregated 

 species, species in process of differentiation, varieties, local forms, geographical races, 

 climatic forms, or by any other name ; but there are two things that we may not do, we 

 may neither elevate them to the rank of species nor ignore their existence. 



The great stumbling-block which has prevented so many ornithologists from practically 

 accepting the Darwinian view of species is the want of a hard-and-fast line between species 

 and subspecies. A moment's consideration must convince everyone who accepts the theory 

 of Evolution that between absolutely segregated species and species which are only 

 beginning to segregate there must be species which are in various states of segregation. 

 Some species are so completely differentiated from their nearest relations that they may 

 inhabit the same area without any cross-breeding between them. Others not quite so 

 absolutely differentiated may be made to cross in confinement, the produce being barren 

 hybrids. A third stage towards imperfect differentiation may be represented by two 

 nearly allied species, which occasionally cross in a state of nature, but the produce being 

 barren the hybrids die off without leaving any descendants. The last stage of cross- 



Theory of 



Evolution 

 practically 

 ignored by 

 ornitholo- 

 gists. 



Importance 

 of recogniz- 

 ing sub- 

 species. 



Classifica- 

 tion of 

 species. 



