MIGRATION. 295 



confused.* The possibility thus suggested receives, I think, 

 some countenance from the following fact. In "Animal 

 lutelligence " I recorded a number of observations which had 

 been made by Sir John Lubbock on the sense of direction as 

 exhibited by ants. These experiments yielded results of a 

 most definite nature, and thus led Sir John to conclude that 

 ants are endowed with the sense of direction in a singular 

 degree. Subsequently, however, he has found (accidentally 

 in the first instance) that in all these experiments the ants 

 found their way by observing the direction in which the light 

 was falling; so that, as long as the source of light was 

 stationary, no matter how many times he turns them round 

 upon a rotating table, when the rotation ceased they knew 

 their road to and from the hive as well as they did before the 

 rotation; whereas, if the source of light were shifted, the 

 insects at once became confused as to their bearings, even 

 though not rotated at all.t Now if ants thus habitually 

 guide themselves by observing the direction in which the 

 light is falling (i.e., the position of the sun), I do not see why 

 migratory birds should not be assisted by similar means. 



This, however, I only put forward as a conjecture. The 

 fact that migratory birds, like many other animals, are in 

 some way able to hold a true course in order to reach a par- 

 ticular locality, is a fact which confessedly we are not able to 

 explain. But — and this is the most important point for us — 

 our inability to explain this fact in the present state of our 

 information, is no objection to the theory of instinct on which 

 we are engaged. We cannot doubt that the fact admits of 

 some explanation, and when we certainly know, what this 

 explanation is, we shall first be able to ascertain -whether the 

 faculty of way-finding is or is not compatible with the 

 foregoing theory of the evolution of instinct. 



Let ns turn now to the second of the two assumptions 

 above alluded to as necessary in order to embrace the facts of 

 migration under the theory — viz., the assumption that some 

 at least among migratory birds must possess, by inheritance 

 alone, a very precise knowledge of the particular dii'ection to 



* See Professor Newton in Nature, vol. xi, p. 6, who says, " Dark cloiidy 

 nights seem to disconcert the travellers. On such nights the attention of 

 others besides myself has often been directed to the cries of a mixed multitude 

 of birds hovering over this (Cambridge) and other towns, apparently at a 

 loss whither to proceed, and attracted by the light of the street lamps." 



t See Jonrn. Linn. Soc, 1883. 



