224 OF MASTICATION AND DEGLUTITION. 



with an epithelium analogous to cuticle, (176) and is 

 lubricated by a very smooth mucus. 



350. This canal receives the approaching draught or 

 bolus of food, contracts upon it, propels it down- 

 wards, and, in the case of the bolus, stufi's it down, 

 as it were, till it passes the diaphragm and enters the 

 stomach. 



NOTES. 



(A) Saliva is composed of 



Water - - 992 . 9 



A peculiar animal matter 2 . 9 



Mucus - 1.4 



Alkaline muriates 1 . 7 



Lactate of soda and animal matter . 9 



Pure soda O . 2 



1000 . 0* 



What Berzelius calls mucus, Professor Thomson and Dr. Bos- 

 tock regard as albumen. It is insoluble in water, and when 

 incinerated, but not before, yields a large portion of phosphate 

 of lime. The tartar of the teeth arises from its gradual decom- 

 position upon them, and consists of 



Earthy phosphates - 79 . O 



Uridecomposed mucus 12 . 5 



Peculiar salivary matter - 1 . O 



Animal matter soluble in muriatic acid 7 5 



600 . Of 



(B) The glottis, when sound, may be sufficiently closed inde- 

 pendently of the epiglottis. M. Majendie saw two persons perfectly 

 destitute of epiglottis who always swallowed without difficulty. 

 Precis Elementaire, T. ii. p. 63. 



* J. Berzelius, Mcdico-Chirurgical Transactions. Vol. iii. p 242. 

 t Berzelius. 



