TASTE 29 
relation to swimming, but it sometimes happens that they have 
been transformed into tactile organs, as in the deep-sea form 
(Evetmophorus) represented in fig. 1034. Snakes employ their 
tongues as tactile organs, as 
also do Woodpeckers and Ant- 
eaters. This, however, is pro- 
bably only an extension of the 
original duties, for the primary 
use of the tongue seems to be 
that of a tactile organ in re- 
lation to the mouth-cavity. 
TASTE 
Sensations of Taste are pri- 
marily important because they 
assist in the selection of suit- 
able food. The stimulus is a _ Fig. 1035.—Taste-Organs of a Wasp. a, Under side of 
chemical one, and consists of 5 suueutep,euyone 
substances in solution. We 
know but little about the gustatory organs of lower forms, but 
as these show a preference for certain kinds of food it is pro- 
bably correct to assume that such organs are present. In the 
Earth-Worm, for example, groups of modified epidermal cells 
in the neighbourhood of the mouth are very 
likely related to taste. 
Certain regions of the mouth-parts of some 
Insects are studded with minute pits, beneath 
each of which is a sense-cell, drawn out ex- 
ternally into a short bristle, and continuous with 
a nerve-fibre internally. They are present, for 
example, in Bees and Wasps, and are almost aren 
certainly of a gustatory nature (fig. 1035). Ce I ea aee 
Cuttle-Fishes and many Snails possess a enlarged. The bud’ contains 
slender taste-cells, the exter- 
sense-organ on the floor of the pharynx, below  jarends of which project into 
the front end of the rasping-ribbon. It pro- 23M Pitconinuouswith the 
bably has to do with taste. 
In Lung-Fishes, Amphibians, Reptiles, Birds, and Mammals 
the organs of taste consist of groups of sense-cells in the lining 
of the mouth-cavity, and since this cavity is developed as an 
