BEAVER CANALS. 383 



question the fact that beavers form these canals, as they 

 form their dams, with a far-seeing perception of the suit- 

 ability of highly artificial means to the attainment of 

 particular ends, under a variety of special circumstances. 

 Mr. Morgan observed one or two instances where the land 

 included in a wind or loop of a river was cut through by 

 a beaver canal across the narrowest part, ' apparently to 

 shorten the distance in going up and down by water.' 

 Judging from the figures which he gives, drawn to 

 measurement, there can be no question that such was the 

 object ; and as these structures may be one or two hun- 

 dred feet in length, and represent the laborious excavation 

 of some 1,500 cubic feet of soil, the animals must be 

 actuated by the most vivid conception of the subsequent 

 saving in labour that is to be effected by making an arti- 

 ficial communication across the chord of an arc, instead 

 of always going round the natural curve of a stream. 



Regarding now together all these facts relating to the 

 psychology of the beaver, it must be confessed, as I said 

 at the outset, that we have presented to us a problem per- 

 haps the most difficult of any that we have to encounter 

 in the whole range of animal intelligence. On the one 

 hand, it seems incredible that the beaver should attain to 

 such a level of abstract thought as would be implied by 

 his forming his various structures with the calculated pur- 

 pose of achieving the ends which they undoubtedly sub- 

 serve. On the other hand, as we have seen, it seems 

 little less than impossible that the formation of these 

 structures can be due to instinct. Yet one or other hypo- 

 thesis, either singly or in combination, must be resorted 

 to. The case, it will be observed, thus differs from that 

 of the more wonderful performances of instinct elsewhere, 

 such as that of ants and bees, inasmuch as the perform- 

 ances here are so complex and varied, as well as having 

 reference to physical principles of a much more recondite 

 or less observable nature. The case from its theoretical 

 side being thus one of much difficulty, I think it will be 

 better to postpone its discussion till in * Mental Evolu- 

 tion ' I come to treat of the whole subject of instinct in 

 relation to intelligence. 



