VESSELS OF ANIMALS. 1 O.'J 



anhelatioii I yet does this little cartilage, the epiglottis, so 

 efTectually interpose its office, so securely guard the entrance 

 of the windpipe, that while morsel after morsel, draught 

 after draught, are coursing one another over it, an accident 

 of a crumb or a drop slipping into this passage — which nev- 

 ertheless must be opened for the breath every second oi 

 time — excites in the whole company not only alarm by ita 

 danger, but surprise by its novelty. Not two guests are 

 choked in a century. 



There is no room for pretending that the action of the 

 parts may have gradually formed the epiglottis : } do not 

 mean in the same individual, but in a succession of genera- 

 tions. Not only the action of the parts has no such tenden- 

 cy, but the animal could not live, nor consequently the parts 

 act, either without it or with it in a half-formed state. The 

 species was not to wait for the gradual formation or expaxi- 

 sion of a part which was from the first necessary to the lite 

 of the individual. 



Not only is the larynx curious, but the whole windpipe 

 possesses a structure adapted to its peculiar office. It is 

 made up — as any one may perceive by putting his fingers 

 to his throat — of stout cartilaginous ringlets, placed at small 

 and equal distances from one another. Now this is not the 

 case with any other of the numerous conduits of the body. 

 The use of these cartilages is to keep the passage for the aii 

 constantly open, which they do mechanically. A pipe with 

 soft mem.branous coats, liable to collapse and close when 

 empty, would not have answered here ; although this be the 

 general vascular structure, and a structure which serves 

 very well for those tubes which are kept in a state of por- 

 ^^etual distention by the fluid they enclose, or which aObrd 

 a passage to solid and protruding substances. 



Nevertheless — which is another particularity well v^\ 

 thy of notice — these rings are not complete, that is, are not 

 cartilaginous and stiff all round ; but their hir ler part, 

 which is contiguous to the gullet, is membranous md soft. 



