ii2 ANIMAL LIFE UNDER WATER 



taking their fish meal, and their gizzards were, 

 respectively, filled .with tea leaves and greasy 

 material; the fish, in consequence, could not 

 enter the gizzard to be triturated. 



The fifth bird contained nine almost disap- 

 pearing bodies of vertebrae^ one whole and one 

 broken air vesicle. 



In the sixth bird both gullet and gizzard were 

 absolutely empty, but the gut jvas full of blue 

 material. 



The last bird, as stated, had not taken a 

 blued sprat. 



Other experiments which I have carried 

 out have confirmed this rapid rate of diges- 

 tion. 



With some of the large gulls, e.g. the great 

 and lesser black-backed, evidence that the bird 

 has taken a fish is removed even more rapidly, 

 for towards the end of digestion these birds dis- 

 gorge the bones remaining in the gizzard. Large 

 colonies of lesser black-backed gulls nest on the 

 island of Rona, and the ground is covered with 

 collections of disgorged bones. 



In the wild state a lesser black-backed gull 

 can digest a pound codling in four hours, so that 

 when the remains of the triturated bones are 



