230 THE WONDER OF LIFE 



work their way into fatal culs-de-sac. Mr. W. L. Bishop 

 reports that in the water-works of Dartmouth, Nova 

 Scotia, eels caused considerable trouble by continually 

 getting into the water-mains, and blocking the service- 

 pipes. 



Some Difficult Phenomena 



' Feigning Death '. It is well known that many 

 Crustaceans and Insects become absolutely motionless 

 when suddenly disturbed. There they lie, without moving 

 a feeler or a limb, as if they were dead. This may be very 

 useful when they are being hunted by enemies who only 

 snap at moving things, who perhaps do not see them 

 unless they move. The phenomenon is very famihar and 

 very puzzling. Whether it is a physiological faint or an 

 instinctive feint, who can tell us. But it is admitted by all 

 that in the lower animals it is not a deliberate ' playing 

 ' possum ' and that it is not a ' fear paralysis '. 



Bohn deals with the so-called ' feigning death ' by 

 pointing out that it comes into line with ' differential 

 sensitiveness ', which is exhibited by some of the lower 

 animals in face of a sudden change in the environment. 

 Single-celled animals and tube-inhabiting worms show it 

 equally well ; they retract and remain quiet ; the duration 

 of their passivity varies with the hght and temperature; 

 after several experiences in succession the reaction dwindles 

 away. There is a strong suggestion here of the so-called 

 ' death-feigning ' in insects and crustaceans, which follows 

 all sorts of stimuli, which varies in its duration with the tem- 

 perature and the illumination, which wanes after it has been 

 brought on repeatedly. The creature passes into a strange 



