INSTINCT, OR HEREDITARY IMPULSE? 205 



that the knowledge of where to migrate is a mysterious 

 gift of Nature, the miraculous quality of which is 

 attempted to be concealed under the semi-scientific term 

 of instinct, appears to be without any foundation in fact. 

 It appears that each individual bird has to find out its 

 own proper winter quarters for itself, and learn the way 

 thither as best it may. That birds have keen organs of 

 sight is a fact well known to all who have watched them 

 obtaining their food or eluding their enemies. That they 

 must have wonderful memories for place is shown by the 

 distance they roam from their nests which, however well 

 concealed, they seem to have no difficulty whatever in 

 finding again. Amongst true migratory birds, that is 

 amongst birds which have a winter as well as a summer 

 home, as distinguished from gipsy migrants who per- 

 petually loaf about on the outskirts of the frost during 

 winter, continually changing their latitude with the tem- 

 perature, it appears to be a general rule that the farther 

 north a species goes to breed the farther south it goes to 

 winter. It is not known if this applies to individuals as 

 well as to species. The various times of arrival of many 

 species of birds in most latitudes of Europe are well 

 known and carefully recorded, but of the dates of 

 departure from the various latitudes of Africa where 

 they winter we know little or nothing, otherwise this 

 question might easily be settled. It is obviously much 

 easier to record the date of arrival of a bird than of its 

 departure. In the one case a single entry is sufficient ; 

 in the other, memoranda may have to be daily recorded 

 for weeks. At Valkenswaard, in Holland, I noticed that 

 the earliest migrants were those with the widest range. 

 Birds whose breeding- range extended to or beyond 

 Britain were the earliest to breed, whilst those whose 

 eggs I was most anxious to obtain, those whose breeding- 



