I'ACKAUD.] MRXTAL rOWEUS OF IXSECTS. 371 



tind keep tliem out of sight for a number of da^'s, sometimes 

 for a fortniglit, it is sufficient to kill one or two ants on the 

 trail whicli they follow descending the wall. This I have 

 recently done as high up as I can reach, three or four feet 

 above the mantel. The moment this spot is reached an ant 

 turns abruptly and makes for home ; and in a little while 

 there is not an ant visible on the wall." 



Sir John Lubbock, who has studied the ways of ants, 

 remarks that "it is wonderful how much individual ants 

 appear to differ from one another in character." 



Instinct is known in a few cases among insects, as well as 

 other animals, to be variable. This is probably due to their 

 power of discrimination, such as the higher animals un- 

 doubtedly possess. It has been asked, sa3's Mr. Darwin, 

 that if instinct be variable, "why the ability to use some 

 other material when wax is deficient has not been granted to 

 the bee?" "But," he answers, "what other material could 

 bees use? They will work with and use, as I have seen, wax 

 hardened with vermilion and softened with lard. Andrevv 

 Knight observed that his bees, instead of laboriously collect- 

 ing propolis, used a cement of wax and turpentine, with 

 which he had covered decorticated trees. It has lately been 

 shown that bees, instead of searching flowers for their pollen, 

 will gladly use a ver}- different substance, namely, oatmeal." 

 These instances seem to show that insects take the most 

 advantageous means offered to them by nature for the ac- 

 complishment of their ends, that the\^ individuall}' exercise 

 a choice, and that instinct varies in different individuals of a 

 species. Within an exceedingly limited range insects exer- 

 cise choice, and are free agents. They adapt themselves to 

 new circumstances, and while there is perhaps little or no 

 progress in the minds of individual animals, they somehow 

 as a class keep pace with a changing, progressive world. 

 No one will deny that creation has not been tending up- 

 wards, that higher forms of animal life have not on the 



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