122 NATURAL THEOLOa"^. 



VI. Another exquisite structure, differing, indeed, from 

 the four preceding instances, in that it does not relate to the 

 conveyance of fluids, but still belonging, like these, to the 

 class of pipes or conduits of the body, is seen in the larynx. 

 We all know that there go down the throat two pipes, one 

 leading to the stomach, the other to the lungs — the one be- 

 mg tlie passage for the food, the other for the breath and 

 voice : we know also, that both these passages open into the 

 bottom of the mouth — the gullet, necessarily, for the con- 

 veyance of food, and the windpipe, for speech and the mod- 

 ulation of sound, not much less so : therefore the difficulty 

 was, the passages being so contiguous, to prevent the food, 

 especially the liquids, which we swallow into the stomach, 

 fi'om entering the windpipe, that is, the road to the lungs — 

 the consequence of which error, when it does happen, is 

 perceived by the convulsive throes that are instantly pro 

 duced. This business, which is very nice, is managed in 

 this manner. The gullet, the passage for food, opens into 

 the mouth like the cone or upper part of a funnel, the capac- 

 ity of which forms indeed the bottom of the mouth. Into 

 the side of this funnel, at the part which hes the lowest, 

 enters the windpipe by a chink or slit, with a lid or flap like 

 a little tongue, accurately fitted to the orifice. The solids 

 or liquids which we swallow pass over this lid or flap as 

 they descend by the funnel into the gullet. Both the weight 

 of the food and the action of the muscles concerned in swal- 

 lowing contribute to keep the lid close down upon the aper- 

 ture while any thing is passing ; whereas, by means of its 

 natural cartilaginous spring, it raises itself a little as soon as 

 the food is passed, thereby allowing a free inlet and outlet 

 for the respiration of air by the lungs. Such is its struc- 

 luie ; and we may here remark the almost complete success 

 of the expedient, namely, how seldom it fails of its purpose 

 compared with the number of instances in which it fulfils 

 it. Reflect how frequently we swallow, how constantly wp 

 breathe. In a city feast, for example, what deglutition, what 



