Introduction 



ture of food. It is the sense on which almost total dependence is 

 placed for protection. 



We are walking along the grassy margin of a lake. In a 

 small cove ahead, screened by shrubbery, a green frog gives a 

 vigorous croak. A second frog, a third, then many others, join 

 till there is a harsh medley of sounds. This continues for some 

 time; suddenly one loud voice stops, and instantaneously all are 

 hushed. Why? We were trying to see through the shrubbery, 

 and although perfectly silent, set a long flexible branch swayinjg, 

 which the frog evidently saw. Shall we say, as do myth and 

 story, that frog orchestras have leaders who intentionally signal 

 the others when to begin, are on the watch, and again give an 

 intentional signal on the approach of danger? Not at all. 

 Human interpretations will not serve for the frog world. The 

 following is the explanation. 



Frogs are extremely alert in sight and hearing, especially 

 in sight. There was no movement anywhere in the horizon of 

 the pond, and one frog gave expression to the physical joy of 

 existence. This croaking was evidence to all the other frogs that 

 there was no danger present; their eyes gave the same proof of 

 safety that the first frog had gained, and one by one they joined 

 in the chorus. The bushes moved. One frog saw the motion 

 (not necessarily the frog that croaked first), was frightened, and 

 responded with instant silence. Perhaps others saw also; if 

 not, the sudden hushing of the one voice implied danger, and 

 every frog obeyed an impulse of fear and became silent. That is 

 all. Except that we have reasoned it out, while the frogs felt 

 and acted only. 



Frogs see small objects best at a distance of three or four 

 feet. They will very often let a fly or worm crawl immediately 

 under their " noses " while they are staring with eager eyes far 

 ahead. Toads are' less far-sighted than frogs. However, frcgs 

 may see an approaching enemy — a person, a bear, or a large 

 bird — ten or more feet away, that is they may give a motor 

 response when the enemy is at that distance. 



There is the familiar " splash " ahead. One frog has seen 

 us. A second " splash," and a third, long before we can approach 

 near enough to see the frog blending as it does with the colours 

 of the bank. These second frogs and others ahead have the ad- 

 vantage in escape over the first, for they were put on the alert 



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