484 THE GENERAL PRINCIPLES OF ZOOLOGY 



instinctive, no choice is exercised between nutritious and non- 

 nutritious substances ; the ability to distinguish is acquired 

 through experience. Flying is instinctive with insects and with 

 some birds. Swimming and diving are instincts with waterfowl. 

 The red-winged blackbird builds its nest in marshy places, 

 often on branches overhanging the water, and the young not 

 infrequently fall into the water before they can fly ; when this 

 accident occurs they at once inflate themselves and thus readily 

 keep afloat. The cowbird lays her eggs in the nests of other 

 birds ; on hatching, the young cowbird is frequently much more 

 developed than the rightful inhabitants of the nest, and has 

 been observed to lift and push them out so that they are left to 

 die while the cowbird remains in sole possession. In these 

 instances there is no possibility of previous instruction or expe- 

 rience, factors which we must always eliminate from purely 

 instinctive actions. Some wasps sting certain other insects, 

 such as bees, flies, and beetles, in such a way as to paralyze 

 them without killing them, and then place them in their nests 

 beside their eggs and seal them up to serve as food for the 

 young when they shall have hatched. It is often quoted as 

 a remarkable example of instinct that the wasp knows just 

 where to sting its prey and render it helpless without killing it, 

 but more careful observations have shown that the prey is by 

 no means always stung in the same place but in a variety of 

 places, and that after being sealed up in the nest, many die, and 

 the developing wasps appear to thrive as well on the dead as on 

 the living. The acts of stinging and of the storing up in the nest 

 are, however, acts of pure instinct, and the latter is of consider- 

 able complexity. Fear is often spoken of as an instinct ; there 

 is much evidence, however, to show that it is due to experience. 

 Many young animals exhibit no fear at the first sight of man; 

 young birds are frightened at the first approach of a hawk, but 

 they are equally afraid of a harmless sheet of flying paper. 



We may now inquire what part consciousness plays in instinc- 

 tive behavior. It seems to be pretty generally agreed bv writers 

 on this subject that consciousness is present to a greater or less 

 extent, and instinct has even been defined as conscious reflex 

 action. We have already noted that it is only the first perform- 

 ance of an automatic act that can really be called instinctive, 





