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 
eleased 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 
‘1 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. 
