WHAT GUIDES BIRDS DURING THEIR MIGRATIONS? 139 



this knowledge in the absence of parents or any kind of teachers 

 during the three stages of their metamorphosis. However much 

 we may be disinclined to admit that in regard to many of the 

 phenomena connected with migration we are at the limit of our 

 knowledge, we can nevertheless hardly deny in the above case, and 

 in that of von MiddendorfFs Samoyedes, the operation as a means 

 to an end of an instinctive and unconscious agenc}^. It would in 

 any case be interesting to become acquainted with some hypothesis 

 which might appear to help us over this difficulty also, especially 

 as, in the case of the Samoyedes, there was no question of a definite 

 migration route travelled over from primitive times ; but we had 

 the fact of these people being capable of orientating themselves 

 from all points to which Middendorff betook himself. 



It may not be out of place here to refer to the inexplicable 

 manner in which dogs are able to find their way back to their 

 homes from very long distances. Among many cases of this kind 

 reported in periodicals, I will select one which a few years ago was 

 related in the Hamburger Correspondent. The owner of a villa 

 outside of Hamburg presented a large dog to an acquaintance 

 from Aachen (Aix-la-Chapelle), who was on a visit to his house. 

 The animal was put into the dog compartment in the train and 

 conveyed to Aix-la-Chapelle (Aachen), where, however, he managed 

 to run away, reappearing some few days after in a very reduced 

 condition at the home of his former owner. The following is 

 another case of the same kind, based on personal information from 

 the owner of the dog, and above all doubt : A dachshund, about 

 a year old, was put into a sack on the estate of its owner and taken 

 in a waggon to a farm eight miles off'. Arrived at its destination 

 the dog was liberated, but disappeared, and was back home again 

 before the return of the waggon ! According to the statements of 

 some field-labourers, it had taken the shortest road home, straight 

 across the fields. A brother of mine, who is a farmer out in Texas, 

 told me it was quite a common occurrence there for cattle which 

 have been driven more than two hundred miles out into the country 

 to return to their native home across pathless tracts and forests. In 

 what conceivable way is it possible to explain such facts as these ? 



In the preceding discussion by far the largest number of facts 

 brought under consideration have related to the land routes of 

 migratory hosts. We have however still to bring under the reader's 

 notice a theory which has been established to explain the crossing 

 of wide seas by migrants, more especially in relation to the occur- 

 rence of American birds in Europe. As already intimated, it was 

 considered absolutely impossible for a bird to traverse a stretch of 

 water at least sixteen hundred miles in breadth, which is the extent 



