94 T>r. Latham^ Effay on the Trachea or Windpipes of Birds. 



dive with fuch facility as they are known to do. The Wild Swa?^ 

 in which we obferve a great elongation added to a peculiar curvature 

 of the windpipe, is able to hold its head for a length of time under 

 water in fearch of food ; but we have no authority for faying whether 

 it can do fo a longer time than the Tame Swan ,in which no fuch pecu- 

 liarity is feen. Befides, the common Crane, and others of the Ardeu 

 genus, which have not in their power even to fwim, are endowed 

 with a much greater elongation and curvature of the windpipe 

 than the Wild Swan. In refpecl to what affiftance fuch a conftruc- 

 tion of parts as abovefaid may afford to the tone of voice, I will not 

 venture here to affirm ; yet it cannot be denied that fome birds are 

 able to utter very loud founds without fuch aid— witnefs the Cock, 

 Peacock, and others* We fee Nature's operations and admire them 

 in courfe, yet cannot always comprehend the utility of her works ■ 

 and this feems one of her defigns concerning which we are not at 

 all clear. It, too, muft be confefled, that the whole we have been 

 able to obtain by our fcru tiny into this fubjecT: is, the fecurity of a 

 mark of didinclion, in refpecl to- feveral fpecies concerning which 

 we have been more or lefsin a ftate of uncertainty. 



1 am aware likewife that anatomifts have done much in regard to 

 the difcovery of fex, by obferving the teficles of the male, which 

 confift of two whitiiTi glandular bodies placed juft below the lungs, 

 clofe to the back-bone, and the ovaries, or clufters of eggs, fituated in 

 the fame place, in the female. It is true that the fix may, by at* 



* How far the difcovery of the difperfion of air-veflUs, which are found among the 

 flefhy parts of birds, pervading more or lefs even the bones themfelves, and communi- 

 cating with the lungs, may contribute to their being able to dive and flay fo long under 

 water, or whether this circumftance may a (lift in voice, fong, or flight, is not for us here 

 to determine. The matter is certainly worth further enquiry, but cannot make any part 

 of this efiay, further than to recommend the perufal of a Treatife on the fubjeft by our 

 late friend Mr. John Hunter, in the Philofophicai Tranfadions.-See vol. lxiv. p. 205. 



tending 



