EXANIPLES OF INSTINCTIVE ACTS. III•: Pecking, walking, scratching themselves, preen ing their down and feathers, stretching up and flapping their wings, scratching the earth, squat ting down and dusting themselves, scattering and crouching when alarmed, making the danger churr and other sounds.
In ducks: The wily they seize and mumble their food in the bill. their swimming. piping, smoothing- the down of the breast with their hills, etc. Alligators on hatching rush with open at anything presented to them, and bite it.
In the higher animals, as birds and mammals, it is more dillieuit. to separate instinctive from intelligent acts. The migrations of birds, and perhaps of fishes, are variable, and Darwin says that this instinct "is occasionally lost." It should be observed that the 1114;r:10011'4 I if birds, as of other animals, locusts, the reindeer, lemming, ut•., are primarily reflex in their nature, being initiated by cold or the lack of food.
Typical examples of the most striking and in explicable instincts are the nesting habits of spiders, of the social insects, such as ants, wasps, and bees, those of birds, also of the muskrat and beaver, the mode practiced by worker bees ar ranged in files of ventilating by a peculiar move ment of their wings, the well-closed hive, and the building of cells of the honeycomb by the ltive-bee.
Our present knowledge of the two chief groups of instincts may roughly and provisionally be classified thns: 11 hellos fret mingled with associative meal bry (consciousness or inicHigeacc): 'Ala Amphibia (tree-frog).
Fishes (certain bony fishes).
Insects (especially the social species). Crust:leen (certain lobsters and crabs). Spiders.
Cephalopod mollusks. Snails (Helix).
(21 lIcjlex arts wily: Scorpion.
King-crab.
Sharks and flounders. Aseidians.
Mollusks, bivalves (pcleeypods), and many univalves (gastropods).
Echinoderms.
I.Vorms (including annelids).
Crelenterates, polyps. and octillions.
Sponges.
Protozoa (amretxr. monads. and infusorians). The highest form of instincts are those of care for the young, or the eggs and nest, as shown by ants, certain fishes, and especially by birds and mammals.