What is the property manifested by living organisms, and the elements and tissues of which they are constituted, of responding to the action of stimulants; irritability; as, nervous excitability called?

excitability — (Physiol.) The property manifested by living organisms, and the elements and tissues of which they are constituted, of responding to the action of stimulants; irritability; as, nervous excitability. (Webster's 1913.)