6 SECRETS OF ANIMAL LIFE 



Cyon's theory that birds (notoriously deficient in 

 the sense of smell of the ordinary kind) nose their 

 way home through the air, feeling the direction, 

 strength, and temperature of the wind as it plays 

 on the olfactory mucous membrane. The nasal 

 chambers of two Noddy terns were filled with warm 

 wax and varnished over, and the birds were sent 

 to Key West, 65 miles distant, where they were 

 released at two o'clock in the afternoon. At day- 

 break next morning both birds were on their nests 

 just as usual. Thus it may be inferred that there 

 is not in the nasal cavity of terns any special tactile 

 or olfactory sensitiveness which functions in the 

 homing. The observers propose to inquire whether 

 there may be on other parts of the body such as 

 eyelids, ear-covering, mouth cavity any tactile or 

 thermal nerve endings which may assist the birds 

 in reacting to slight differences in pressure, tempera- 

 ture, and humidity which they may encounter on 

 their flight. 



So the matter stands at present the remarkable 

 fact of untrained birds successfully reaching from a 

 great distance a known but invisible goal surrounded 

 by apparently trackless sea. It goes without saying 

 that there are speculative theories galore, but 

 what Professor Watson and Dr. Lashley are work- 

 ing towards is a scientific interpretation. Natural- 

 ists have appealed to magnetic sense, topographical 

 memory, registration of movements, telepathy, 

 and so on at least nine theories have been advanced 

 : but the solution of the riddle is still in the future. 



