No. 484] CLOSELY RELATED SPECIES 217 



If we were right in what was said above about the specific 

 effects of different modes of evolution upon (hstribution, the 

 first question to be asl^ed of the geographer is this: Are species 

 universally so distributed that each one occupies a region of its 

 own, or a habitat of its own; so that even the nearest related 

 species are strictly separated in sj)a('c. either in the broad geo- 

 graphic sense, or at least topograpliicallv / 



It is to be noted that the inquiry lias iwo >t<'i)>. or >iauv- The 

 first relates to the distribution of organisms in thr br.,a.Icr x-iisc. 



identical districts, or have largely coincident ranuv-. in many 

 cases. The adherents of the Mutation Theory exi.ect to lind a 

 considerable proportion of sucii instances, ("ertain of ii^ oppo- 

 nents have believed that the advance of the theory might 1 .l.x ked 

 on this first level. But if their efforts fail hvvv tluy are i)repare(l 

 to fall back upon the second line of <lefenee. 'n.e >.(<.nd stage 



in relation to ecological condition^, and a>k> whether anv of the 

 allocated forms — if some are found cxi^i >i<le ly --idc with- 

 out even local .segregation. Di.sciples of de \'rie> expeei thai 

 instances will occur in such number> as lo s;iti>fy the ihMnaud- 

 of their theorv; while the opposit(> pariv thinks ilmi practically 

 no in.stances will be discovered giving counienance to tl.,- idea 

 of :\Iutaiion. Tluy expeei that all caM-. ..f -eneral geoo-raphie 



tion, alfording practical is,,lation: and so hop.' to withstand th(> 

 final a.s.sault of the Mutationi>|s. 



The application of the botanical eviiK-ncc j)resented in thi- 

 paper is to the first stage of the iiupiiry. .^omc of it is manifotis 

 applicable to the second stage also. 



Specific 1 )isTh'i iu i i<>\ i\ tiik Am.mai. Kin<;i).»m 



