Herrick, Verve Components. 307 
hand, it is easier to correlate the data as we go along, the syn- 
thesis accompanies the analysis, and the possibility of experi- 
mental control should keep the student in closer touch with his 
guiding facts and discourage general speculation. 
As a concrete illustration of the practical method of apply- 
ing the doctrine of nerve components in the functional analysis 
of the nervous system, we may summarize briefly the progress 
which has been made up to date in the study of the gustatory 
system. 
In man, as is well known, the sense of taste is not very 
highly developed. The peripheral organs, or taste buds, are 
situated chiefly on the tongue, those near its base innervated 
by the glossopharyngeal nerve, and those near the tip probably 
by the chorda tympani of the facial nerve. But the gustatory 
pathway toward the brain is very imperfectly understood and 
many points are still in controversy, while the central path is 
almost wholly unknown. 
; But in certain fishes, such as the carp and cat fish, this 
system of sense organs is enormously exaggerated. Taste buds 
are found, not only in the mouth, but all over the outer skin 
- and barblets. Direct experiment shows that these fishes actually 
do taste with these superficial sense organs—unlike some peo- 
ple, their taste is not all in their mouth. 
The experiments made on the cat fish (Ameiurus) show 
that these fishes seek their food by feeling for it with the barb- 
lets and by means of them they discriminate between edible 
and non-edible substances, that they habitually use both the 
sense of touch and the sense of taste for the purpose and that 
they can be taught to discriminate between tactile and gusta- 
tory stimuli applied to the skin and will turn and snap up sav- 
ory substances and reject objects which feel like them but are 
devoid of taste. 
The exact distribution of the gustatory sense organs has 
been determined and their nerves traced back to the brain. We 
get the gustatory reaction from the skin as described above in 
fishes which possess these cutaneous sense organs, and the reac- 
