110 THE LIFE OF THE FIELDS. 



the beginning of Caesar's exploits. What men do only 

 at intervals birds do frequently, having greater free- 

 dom of movement. 



Who can doubt that the wild fowl come south 

 because the north is frozen over ? The Laplander and 

 the reindeer migrate together; the Tartars migrate 

 all the year through, crossing the steppes in winding 

 and devious but fixed paths, paths settled for each 

 family, and kept without a map, though invisible to 

 strangers. It is only necessary to watch the common 

 sparrow. In spring his merry chirp and his few notes 

 of song are heard on the roof or in the garden ; here 

 he spends his time till the broods are reared and the 

 corn is ripe. Immediately he migrates into the fields. 

 By degrees he is joined by those left behind to rear 

 second broods, and at last the stubble is crowded with 

 sparrows, such flocks no one would believe possible 

 unless they had seen them. He has migrated for food, 

 for his food changes with the season, being mainly 

 insects in spring, and grain and seeds in autumn. 

 Something may, I venture to think, in some cases of 

 migration, be fairly attributed to the influence of a 

 desire for change, a desire springing from physiological 

 promptings for the preservation of health. I am 

 personally subject twice a year to the migratory im- 

 pulse. I feel it in spring and autumn, say about 

 March, when the leaves begin to appear, and again 

 as the corn is carried, and most strongly as the 

 fields are left in stubble. I have felt it every year 

 since boyhood, often so powerfully as to be quite 

 unable to resist it. Go I must, and go I do, some- 

 where ; if I do not I am soon unwell. The general 



