GEOGRAPHICAL VARIATION. Ill 



diverse habitats. These modifications, however, are no more permanent than 

 those found in nature. Indeed, the conclusion I have reached is that the geo- 

 graphical variation is due solely to place variation, which in a particular local- 

 ity is rather constantly in one direction. As far as this species is concerned, 

 although marked geographical variations are found, the evidence is conclu- 

 sive that they are not permanent, and that although the species varies in dif- 

 ferent localities it has not undergone any constitutional change. In Colorado, 

 New Mexico, and western Texas decemlineata has lived for some hundreds 

 of generations. At Chicago it has been a resident of constant conditions from 

 1865 to 1905, a period of 40 years or 80 generations. At this latter place it 

 varies considerably in general color from the condition in Colorado and 

 western Kansas, and yet a period of 80 generations under uniform conditions 

 has not been sufficient to impress upon the species any degree of change. 

 Likewise the long period of time that it has lived in the Southwest has not 

 changed the constitution of the species. As far as the evidence goes, and 

 I believe that in this case it is remarkably complete, since so much is known 

 of the history of the species, it seems certain that this form has not been 

 altered by its existence in any one of a dozen different habitats, and that it has 

 retained the same constitutional structure and character. Place variation only 

 is found, and this is in a constant direction as long as environmental condi- 

 tions remain constant and change only as they change. 



The geographical variations in general color shown by L. multitccniata are 

 of the same nature as those found in decemlineata, and are altered or pro- 

 duced at will in experiment. As far as I can determine they represent, not a 

 permanent condition in the species, but merely a place variation which is 

 constant as long as the conditions of existence are constant and varies as fast 

 and as frequently as its environment varies. An important but seemingly 

 unanswerable question in this connection is, How long must a species be sub- 

 jected to given conditions before it will be permanently changed in a given 

 direction? How long must decemlineata live at Chicago in order that the 

 general color conditions characteristic of Chicago may be so firmly impressed 

 upon its constitution that when it is transplanted into slightly different environ- 

 mental conditions it will retain its Chicago character, at least for some consid- 

 erable time? The evidence from this investigation would indicate that varia- 

 tions produced by different environmental complexes produce only tempo- 

 rary variation and are not incorporated in the constitution of the species, at 

 least not in some hundreds of generations. L. multitccniata has certainly occu- 

 pied its present habitat for a long period of time, at least during thousands 

 of generations, and yet in all this time the place variation tendency of differ- 

 ent localities has not become incorporated in the constitution of the species, 

 and it is tc-day as variable in this respect as it probably was at the beginning. 



