240 



WILLIAM LAWRENCE TOWER. 



hibernation remains at about a constant figure in both the 

 introduced materials at Tucson and in the original materials 

 that have lived continuously at Chicago; second, that the 

 elimination during hibernation takes a great increase in all the 

 second generations tested, from 9.5 per cent, to over 80 per cent., 

 and then in the next following years increases slowly until the 

 sixth, when elimination is complete and continues to be so, no 

 capacity to resist the Chicago winter conditions appearing in 

 any of the Tucson materials in the later generations. 



Beyond question, therefore, some change has taken place as 

 a consequence of the introduction of L. decem-lineata from the 



Behavior in Stocks in original 

 Habitat 



Behavior of Stocks after return to the original 

 Habitat after living at Tucson 



100% 



Behavior of the stocks at Chi- 

 cago, in their original habitat. 



Results of the tests of the materials subjected to the 

 conditions of the deserts at Tucson, Arizona. 



FIG. i. Graph showing the curve of survivals from hibernation, of elimination 

 in preparation for hibernation, and of elimination during hibernation. 



habitat at Chicago into the deserts at Tucson, in the change 

 from a moist habitat into one of intense desiccation during the 

 resting season, which is passed in hibernation. This change is 

 made graphic in Fig. I, showing the line of elimination in the 

 preparation for hibernation, remaining constant throughout the 



