72 PHYSIC. 



nostrils. Such a tendency to gravitate is, during health, effectually pre- 

 vented by the soft palate. Before any substance can pass from the 

 mouth toward the throat, that appendage must be raised, and its rising 

 closes the posterior entrance to the nasal chambers. 



The tongue is the primary agent employed when the animal slakes its 

 thirst. The backward portion of the organ is contracted, and the for- 

 ward part compressed by muscular volition, (d d, fig. 1.) A vacuum 

 would thereby be created, were not the water propelled by atmospheric 



Fio. 2. 



DIAGRAM, (fio. 2,) EXPLANATORY OP THE COMPOXTNI) ACT OP DRINKINQ. 



o a. The water driven backward by the forward dilatation of the tongue and the upward movement of 

 the larynx. 

 b b. The full current forced down the gullet. 

 c. The larynx propelled against the soft palate. 

 dd. The tongue, dilated anteriorly and compressed posteriorly. 

 e. The soft palate. 



pressure into the void thus formed, (a, fig. 1.) The posterior of the 

 tongue is then relaxed, while the anterior division of the organ is pressed 

 against the roof of the mouth, (d d, fig. 2.) The fluid is thereby driven 

 to the backward part of the cavity, (a, fig. 2.) The tongue, during the 

 act, continues to alternate the states of contraction and relaxation, each 

 motion of the lingual agent serving to pump the water into the fauces, 

 (a, fig. 1.) But, before that can be accomplished, the soft palate must 



