BEAVEK — 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, 6 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 w^as 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 wuth 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 s Mental Evolu- 
tion ’ I come to treat of the whole subject of instinct in 
relation to intelligence. 
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