214 APPENDIX II INTENSIVE SEGREGATION. 



be based on some fundamental distinction between species and 

 varieties.* 



The best nomenclature is the one in which the specific distinctions 

 correspond in degree with those that are recognized as specific in other 

 families, and in which a degree of divergence that is considered specific 

 in one part of a genus is considered specific in every part. If the dis- 

 tinctions on which Reeve, Pfeiffer, and Newcomb have founded the 

 species in Makiki and Manoa are received as specific distinctions, then 

 similar distinctions occurring in the forms of other valleys must be 

 recognized as belonging to different species. I by no means contend 

 that these differences should be regarded as specific ; but having re- 

 ceived the three or four forms of Achatinella found in Manoa as good 

 species, it will not do to say that the forms of Achatinella found in 

 Waialei, differing from each other in the same manner and degree, 

 are but one species. 



Notwithstanding the diversity of opinion that will always exist as 

 to how many species should be made of the forms occurring in any one 

 valley, every one will agree that the forms of Bulimella and Achati- 

 nella found in any one valley are quite distinct species from those 

 found in valleys that are ten or twenty miles distant. The lessons we 

 are drawing from the divergence in this family are, therefore, not 

 dependent on any special views concerning the number of species that 

 ought to be received. 



As examples of intergrading species, examine first the types of 

 Achatinella producta, A. adusta, and A. buddii from Makiki; then all 

 the forms of these and the other species of Achatinella found in Ma- 

 kiki, and then the forms found in the successive valleys of the whole 

 mountain range. 



If freedom from intergrading is received as the necessary and suf- 

 ficient test of good species, then a multitude of forms that are only 

 varieties may be turned into good species by burning the forests in 

 alternate valleys on either side of this mountain range. Moreover, if 

 this is the true test of species, the species-maker who throws intergrade 

 forms into the fire is quite consistent, even if not quite frank. 



Whether we call these divergent forms species or varieties, the pro- 

 cess by which the divergence has been produced is a matter of equal 

 interest. Indeed, some evolutionists maintain that one of the chief 

 desiderata in the theory of evolution is an explanation of the origin of 

 varieties.! Variations are deviations from the average, but varieties 



*So far as the necessary material can be obtained the statistical method of 

 testing species is under such conditions the best. 



t See " Evolution and its Relations to Religious Thought," by Joseph Le Conte, 

 published by Appleton & Co., p. 252 



