272 FACULTIES OF BIRDS. 



tumn, although in external appearance the young 

 goose resembles the parent, no trace of aircells 

 can be discovered in its bones, the interior of the 

 bones being then filled with marrow. About the 

 fifth or sixth month the marrow begins to disap- 

 pear. This circumstance, which applies also to 

 other birds, shows with what caution one should 

 form an opinion, from young birds only, on the 

 size of the aircells. In many kinds of birds the 

 aircells of some bones are nearly fully developed, 

 although they have the openings of the bones which 

 lead to the aircells."* 



Not only the bones, but the quills of the feathers 

 also make a part of this contrivance. These, while 

 growing, are filled with an organized pulp ; but as 

 soon as they arrive at their full growth, this pulp, 

 being absorbed, renders them light, and the lightness 

 is increased by air from the atmosphere being in- 

 troduced into their cavity through a small opening 

 at the termination of the furrow where the quill or 

 barrel ends and the plumelets of the feather begin. 

 Air is also introduced in a similar manner into the 

 plumelets themselves. 



" In a journey," says M. Tachard, " which we 

 made to the loadstone mine, M. de la Marre wound- 

 ed one of these large birds which our people call 

 Grand Gosier, and the Siamese Noktho .... Its 

 spread wings measured seven feet and a half. On 

 dissection we found, under the fleshy panicles, very 

 delicate membranes, which enveloped the whole 

 body, which, folding differently, formed many con- 

 siderable pouches, particularly between the thighs 

 and the belly ; between the wings and the ribs, and 

 under the craw, some were so wide as to admit the 

 two fingers ; these great pouches divided into many 

 little ducts, which, by perpetual subdivision, ran into 

 an endless multitude of ramifications, which were 



* Blumenbach, Comp. Anat., 182. 



