530 THE GANNET 



an inch. Here, being interlaced one with another, they 

 constitute a pneumatic coat of no small elasticity. Apart 

 from the air-cells proper, the Gannet must find this extra 

 protection of immense value, when plunging for its prey. 

 Close to the roots of each of these contour feathers, accord- 

 ing to Nitzsch, and on the anterior side, there is a small 

 round aperture, and these apertures I conclude form a 

 passage to the larger cells, through which air can pass.* 

 They are well shown in Mr. Wilson's drawing. In his 

 second sketch the regularity of the roots of the feathers 

 is exhibited in a casting of plaster-of-paris, resting upon 

 the lobes of the liver. 



The (Esophagus. — Having now finished with the air-sacs 

 and cellular cavities, the next most important feature 

 in a Gannet's anatomy is the gullet or oesophagus, an 

 organ justly regarded by Professor MacgilHvray as of 

 primary value in all birds. In the Gannet it is eleven 

 inches in length, and exceedingly dilatable, of which I 

 have had many proofs in my live birds. Macgillivray 

 furnished Audubon's " Ornithological Biography " with an 



* Mr. C. B. Ticehurst writes {in lilt. ) : " I am not sure that this is 

 so, each hole seems to enter into a small space, which is walled in by 

 cellular tissue from the adjoining space ; the communication between 

 each compartment (if there is one) must be small, as I cannot get an^' 

 fluid to flow from one compartment to the next." 



