HI ON ANIMAL LIEE 93 



much greater brilliance, and in these cases the 

 glow seems to be a real love-light, like the 

 lamp of Hero. 



Many small marine animals, Medusae, 

 Crustacea, "Worms, etc., are also brilliantly 

 luminous at night. Deep-sea animals are 

 endowed also in many cases with special 

 luminous organs, to which I shall refer 

 again. 



SENSE OF DIRECTION 



It has been supposed that animals possess 

 also what has been called a Sense of Direc- 

 tion. Many interesting cases are on record of 

 animals finding their way home after being 

 taken a considerable distance. To account 

 for this fact it has been suggested that 

 animals possess a sense with which we are 

 not endowed, or of which, at any rate, we 

 possess only a trace. The homing instinct of 

 the pigeon has also been ascribed to the same 

 faculty. My brother Alfred, however, who 

 has paid much attention to pigeons, informs 

 me that they are never taken any great dis- 



