HOW ANIMALS GET HOME. 201 
and renew their journey in the morning. When snow dis- 
guises the landscape, also, many pigeons go astray. None 
of these circumstances seriously hampers the semi-annual 
inigrations of swallows or geese. They journey at night, 
as well as by day, straight over vast bodies of water and 
flat deserts, true to the north or south. Homing pigeons 
fly northward or southward, east or west, equally well, and 
it is evident that their course is guided only by observa- 
tion. Watch one tossed. On strong pinions it mounts 
straight up into the air a hundred feet. Then it begins 
to sweep around in great circles, rising higher and higher, 
until—if the locality is seventy-five or one hundred miles 
beyond where it has ever been before—it will go almost 
out of sight. Then suddenly you will see it strike off upon 
a straight course, and that course is homeward. But take 
the same bird there a second time and none of these aérial 
revolutions will occur—its time is too pressing, its home- 
sickness too intense for that; instantly it turns its face 
toward its owner’s dove-cot. 
These facts mean something. They show that two defi- 
nite intellectual processes serve to decide for the bird the 
direction he is to take—observation and memory. He gets 
high enough, and turns about times enough, to catch sight 
of some familiar object, and he makes for it; arrived there, 
