THE SENSE OF TASTE

New Zealand Times, Volume L, Issue 11657, 23 October 1923, Page 6

THE SENSE OF TASTE

HOW IT MAY WARN YOU

EVOKING REFLEX ACTIONS.

As with smell, eo as regards taste, there is a tendency to underrate the importance of the sense, writes Professor J. Arthur Thomson in “John O' London’s Weekly.” Man is eo predominantly eye-minded and ear-minded that he naturally ranks the other senses on a lower level, especially when he thinks of the senses os doors of knowledge through which his mind is furnished But the sense organs have the further function of being outposts for receiving useful signals and for evoking almost automatically tho6© useful answers back which we call reflex actions. The sense of taste may save a man’s life by prompting him to turn away from or reject unwholesome food. Moreover, the sense of taste, like that of smell, ia important in Netting agoing the secretion of the digestive juices ana other important operations by which the food is utilised in the food canal. It is not for nothing that “our mouth waters” at the sight of palatable food, and the gustatory preparation for the meal may be of value even if it does go the length of evoking profuse salivary eecreticn.

There are some fishes that have “taste-buds” on the side of their body, and there are many instances of taste organs in situations quite apart from the mouth. But everyone knows, that in man the seat of taste is in the mouth. The taste Jmds are situated not only on the tip and lateral dorsal surface of the tongue, but on other places, such as the soft palate, the opiglotis, and the wall of the pharynx. In early childhood they are more widely distributed thau in tie adult. Thus, the inner surfaces of the cheeks are gustatory in young children. It may be noted that there is much individual variation as wel l as age variation in the number of taste-buds, and that an average number for a single papilla on the tongue of an adult is about 350. There is gustatory individuality justifying tho phrase—‘‘a question of taste.” A taste-bud is a spindle-shaped or flask-eliaped group of cells embedded In the mucous membrane, and usually opening by a small pore. The group consists of a few elongated taste cells, each with a delicate process or hair projecting out of the pore or into its canal when that is present. As the older taste cells become exhausted and disintegrate, now ones are formed to take their place. The buds are richly innervated by fibres which issue in mammals from at least three of the brain nerves.

If a substance is to be tasted it must he brought into contact with the taste-buds in the form of a watery solution. Particles from a distant object may be detected by smell, but taste implies actual contact. In other words, taste cel'ls are contact chemical receptors. It follows that a solid substance cannot be fully tasted unless part of it is chewed, dissolved in the saliva, and moved about so as to come into intimate contact with tho taste cells.

The stimulation of these colls is followed by a message to the brain and the production of a pleasant or unpleasant sensation. In the last case there may be a reflex rejection of the unpalatablo substance, and this has doubtless sometimes been of life-saving Importance—especially long ago, when man was still very ignorant in regard to the wholesome and the unwholesome. When n person dies thromrh having swallowed tho wrong medicine it means that ho did noi/ give the draught time to be tasted. The average time between a taete stimulus and the answer back is estimated at 0.167 of a second, hut this varies considerably according to the nature of the substanoe tasted.