This time, the little beavers did not wait 
so long before coming to the side of their 
mother, for they sensed that they must do 
this. She would not come to them. A third 
and a fourth time Mother Beaver repeated this, 
and then all of a sudden, O-Go guessed the 
secret. The thwack was a signal that his moth¬ 
er was about to dive. Very well! The next 
time, he would dive when she did. “Thwack!” 
There was the signal, and instantly O-Go was 
in the water, and following his mother away 
from the dam. 
Two or three times more, as they plunged, 
O-Go and his mother left the others well be¬ 
hind them, but at last all three of the little 
beavers knew the signal, and would dive as 
soon as it was given. Their learning this lesson 
relieved Mother Beaver of one of the worst of 
her worries, since many times in the life of 
each of them, it would be necessary to dive at 
the first hint of danger. To fail to heed a warn¬ 
ing at such a time as that might mean for them 
death or terrible injury. Thus, O-Go, Ilg, and 
Ela had increased their chances of long life 
through learning the meaning of tail-thwack¬ 
ing. 
There was another method of signalling the 
nearness of danger, and that was by means of 
a sharp, quick whistle. It was necessary for the 
beavers to have this second means of warning, 
29 
