20 OHIO STATE ACADEMY OF. SCIENCE. 
instead of being barely discernable by refined histological methods, 
as in the human body. And the secondary gustatory path, which 
in man is totally unknown, is the largest single tract in the brain, 
both in the cat fish and in the carp! 
The primary gustatory center in the medulla oblongata is 
bilobed, the “facial lobe,” receiving the gustatory fibers from the 
skin and the “vagal lobe” receiving those from the mouth. From 
these lobes there is both an ascending and a descending gustatory 
path. The latter passes down to the point where the medulla 
oblongata. merges into the spinal cord and there terminates in a 
special nucleus which is intimately related to the funicular nuclei, 
a center for tactile sensations. Here the tactile and gustatory 
stimuli are co-ordinated and a common descending bundle (terti- 
ary path) passes back into the spinal cord for the body movements 
necessary to turn toward the food object. The ascending sec- 
ondary gustatory path extends upward to a big nucleus under 
the cerebellum, from which tertiary pathways extend forward 
and downward into the midbrain (chiefly in the inferior lobe), 
then backward by a descending path of the fourth order into the 
medulla oblongata to reach the motor nuclei of the cranial nerves. 
We have already gone far enough into our analysis of these: 
secondary and tertiary gustatory paths to make it perfectly safe 
to predict that all of the habitual gustatory reflexes which we have 
observed in these fishes can be followed anatomically through 
the brain for their entire extent. And since we have the strongest 
reasons for believing that the elementary reflex paths are essen- 
tially similar in mammals and fishes, we expect to find here an 
important guide for further, research in human anatomy. 
So the other sensori-motor systems may be sev erally investi- 
vated, beginning the attack in each case with some species low 
down in the vertebrate series in which this particular mechanism 
is highly developed, and then extending the research to higher 
and lower types. 
We may ultimately hope for a subdivision of the brain which 
shall be both structural and functional, each organ or pathway 
being given its function or meaning in the system as a part of the 
machinery of keeping the body in vital, helpful contact with 
environing forces. The great morphological “head problems,” 
such as the primitive metamerism and the subsequent marvelous 
kalaidoscopic changes in structure and function of the component 
segments, these must all be read through the medium of such an 
intensive study of these factors upon which all differentiation has 
in last analysis depended. 
