SENSE OF TASTE :-PAPILLA OF TONGUE. 
395 
keep up these movements for a considerable period, as if 
carrying on a close conversation. That the Antennae are 
delicate organs of Touch can, therefore, be scarcely questioned. 
Sense of Taste . 
499. The sense of Taste, like that of touch, is excited by 
the direct contact of particular substances with certain parts 
of the body; but it is of a much more refined nature than 
touch, inasmuch as it communicates to us a knowledge of 
properties which that sense would not reveal to us. All sub¬ 
stances, however, do not make an impression on the organ of 
taste. Some of them have a strong savour, others a slight 
one, and others again are altogether insipid. The cause of 
these differences is not understood; but it may be remarked 
that, in general, bodies which cannot be dissolved in water 
have no savour; whilst most of those which are soluble have 
a taste more or less strong. Their solubility, in fact, seems 
to be one of the conditions requisite for their action on the 
organ of taste ; for when that organ is completely dry, it does 
not receive any sensation from solid bodies brought into con¬ 
tact with it, which may have the most powerful taste if re¬ 
duced to a fluid form; and there are substances known, which, 
being perfectly insoluble in water, are insipid if applied to 
the tongue when it is covered as usual with a watery secre¬ 
tion ; but which have a strong taste when they are dissolved 
in some other liquid, spirit of wine for instance. 
500. The sense of Taste has for its chief purpose, to direct 
animals in their choice of food; hence its organ is always 
placed at the entrance to the digestive canal. In the higher 
animals, the tongue is the principal seat of it; but other 
parts of the mouth are also capable of receiving the impres¬ 
sions of certain savours. The mucous membrane which covers 
the tongue is copiously supplied with blood-vessels; and is 
thickly set, especially upon its upper surface, and towards the 
tip, with papillae , resembling in structure those of the skin, 
but larger. These papillae, however, are not all sensory; for 
some, which are of conical form, are covered with a firm horny 
epithelium, and their function seems to be chiefly mechanical. 
These “ conical ” papillae are very strongly developed in the 
tongues of many of the lower Mammalia, to which they impart 
a particular roughness; thus it is by their means that a Dog 
