4.;n Tin: RX8PI&ATO&Y APPARATUS IN MAMMALIA. 



of tho brachiol arteries supply it with blood. Its nerves come from tho 

 recurrent ; they show small ganglia on their track. 



Functions. Except as a tube for the passage of tho inspired and expire < I 

 air, tho trachea performs no other function. 



3. The Bronchi. (Fig. 232.) 



Preparation. After removing tho luiifj; from tho thoracic cavity, it is filled with wnter 

 by fixing the trachea to a water-tap. The bronchi may then be directed by tearing 

 aud triturating the pulmonary tissue. 



Each of tho two bronchi the terminal branches of tho trachea resembles 

 a tree imbedded in tho substance of tho lung, and sending out a multitude 

 of branches. 



Fig. 232. 



BRONCHIAL TUBE, with its Bronchules and Ultimate Ramifications (natural size). 



Disposition. At a short distance from their origin, the bronchi outer 

 the lobes of tho lung, and pass backwards and outwards towards tho 

 superior part of tho base of the organ, giving off in their course largo 

 collateral branches until they themselves are expended. Those branches 

 originate alternately above, within, below, and outwards ; and thus extend 

 in every direction. The first forms an obtuso angle with tho principal 

 trunk, and is directed forwards, to ramify in tho anterior lobulo of the 

 lung ; tho others are detached at an angle more or less acute. All are 

 subdivided into gradually-decreasing branches, which soon become of a 

 capillary diameter, and finally open into tho pulmonary air-cells. (See 

 STBUCTUUK OP THK LUNGS.) 



