PARTS OF ANIMALS, III. in. 



those parts that the neck subserves — viz. the larynx 

 and the oesophagus, as it is called. 



The larynx is present for the sake of the breath : 

 when animals breathe in and out, the breath passes 

 through the larynx. Thus creatures which have no 

 lung {e.g. fish) have no neck either. The oesophagus 

 is the passage by which the food makes its way to 

 the stomach ; so those that have no neck have no 

 distinct oesophagus. So far as food is concerned, 

 however, an oesophagus is not necessary, since it 

 exerts no action upon the food ; and there is really 

 no reason why the stomach should not be placed 

 immediately next the mouth. The lung, however, 

 could not be so placed, because some sort of tube 

 must be present, common to both lungs, and divided 

 into two, by Avhich the breath is divided along the 

 bronchial tubes into the air-tubes : this is the best 

 method for securing good breathing, both in and out. 

 This respiratory organ, then, of necessity, is of some 

 length ; and this necessitates the presence of an 

 oesophagus, to connect the mouth to the stomach. 

 Now the oesophagus is fleshy, and it can also be 

 extended like a sinew. It is sinewy so that it can 

 stretch as the food enters in ; and it is fleshy so that 

 it may be soft and yielding and not be damaged by 

 the food grating on it as it goes down. 



What are called the larynx and windpipe are Larynx and 

 constructed of cartilaginous substance, since the pur- ""° ^'P^" 

 pose they serve includes speech as well as respira- 

 tion ; and an instrument that is to produce sound 

 must be smooth and firm. The windpipe is situated in 

 front of the oesophagus, although it causes it some 

 hindrance Λvhen food is being admitted — as when a 

 piece of food, no matter whether solid or fluid, gets 



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