The brain, lungs, heart, and digestive organs, are called vital organs.
The structure of this nerve is very complicated, and different physiologists ascribe to it various functions. The character of its diseases are not well understood.
Dr. Elliotson, and some other writers On physiology, have detailed cases of death from voluntary suspension of respiration. But these cases are not conclusive, as examinations were not made, so as to determine positively, that death did not result from disease of the heart, brain, or some other vital organ.
Some physiologists impute the sense of taste to the ninth pair of nerves; others, to the twelfth pair; while others, again, contend that taste is the result of a concurrent action of the fifth, ninth, and twelfth pairs of nerves.
The refracting character of differently-formed lenses is illustrated in the works on Natural Philosophy, to which the pupil is referred.