194 



GANNET. 



the air-cells, in the parts already mentioned, have a free communi- 

 cation with the lungs, by means of openings on their surface, through 

 which the air passes readily into them : and it clearly appears there is 

 no diaphragm that confines the air to the regions or cavity of the 

 breast, but that the whole of the abdomen is equally . inflated by inspi- 

 ration through the lungs. 



Thus far have the scientific researches of that anatomist contributed to 

 our knowledge on this subject. No one appears to have noticed the 

 phenomena attendant on the construction of the Gannet, or to what 

 further extent this circulation of aerial fluid is carried in some parti- 

 cular species of birds ; a circumstance which demands our highest 

 admiration, when we contemplate the advantages of such a structure 

 in conducing to the comforts, and perhaps to the very existence of such 

 animals. 



Several Gannets having been subjected to artificial inflation, we shall 

 state the result, and relate the manner in which the experiments were 

 pursued. A pipe was first introduced into the windpipe, (trachea,) and 

 when air was propelled through it, the whole internal cavity of the 

 body was inflated, but no air passed into the external cells between the 

 skin and the body. An incision was then made in the lower part of the 

 abdomen into the body, very near the vent, into which air was forced 

 through a pipe ; the pipe in the windpipe, (trachea,) having been pre- 

 viously stopped, and a similar inflation ensued, without affecting the 

 exterior cells. The pipe was now removed from the windpipe, 

 (trachea,) and upon the air being propelled with force through the 

 pipe near the vent, it readily found its way through the larynx, pro- 

 ducing a noise similar to the sound emitted by the living bird. A small 

 opening was then made in the skin on the left side, about midway 

 between the wing and the thigh, and a pipe introduced, having first 

 stopped those directly communicating with the internal parts. It was 

 now obvious that when air was forced through this orifice, the skin on 

 that side, as far as the middle line of the body, was greatly inflated, 

 extending into the lower part of the neck, along the larger joints of the 

 wing, down the thigh, and also into the cavity of the body ; but the 

 right side was not in the least affected. The pipe at the trachea being 

 now removed, the air produced a similar effect upon the larynx, as 

 before mentioned, but not so loud. Still suspecting that there was a 

 communication between the sides, by means of some valvular apparatus, 

 the right side was subjected to the same experiment ; the result, 

 however, negatived our expectation, the effect produced being similar 

 in every respect. 



