108 Chapter III. 



to feel uncomfortable in their residence on the southern 

 edge of a fir-plantation, they emigrate, bag and bag- 

 gage, to the more shady side on the north. Toward the 

 end of May, 1896, I observed several colonies chang- 

 ing their nests for this reason. If the weather changes 

 and continues to be chilly and rainy, they bundle up 

 once more and go back to the old home. A similar 

 instance, I noticed on June 20, 1896. There had been 

 heavy showers for several days back and many son- 

 guinea colonies that hitherto had lived in earth-nests 

 were moving into old oak stumps ; for these afforded 

 them a better shelter against the penetrating rains. 

 Those who designate as "intelligence" every suitable 

 change in instinctive activities, caused by sense percep- 

 tions and sense experiences in animals, can hardly 

 escape from crediting ants with rather a considerable 

 degree of animal intelligence; for even in the highest 

 mammals we hardly find a higher degree of "psychic 

 plasticity," than is manifested in the above examples 

 by the sanguine slavemakers. However, we have 

 already shown in a former essay (Instinct and Intelli- 

 gence in the Animal Kingdom), that it is entirely 

 wrong to apply the term "intelligence" in this man- 

 ner; for the phenomena in question can be fully 

 accounted for by instinctive sensation and, therefore, 

 they do not supply the least evidence in favor of intel- 

 ligent, mental activity of the animal. Man, of course, 

 in observing such phenomena, can attribute to the ants 

 the following reasoning : "For the last few days it has 

 been raining a great deal. We and our children have 

 become dripping wet. Now, we do not want to get 

 wet again ; therefore, we must move to another dwell- 



