1881, ] Comparative Neurology. 19 
not only a distribution to the viscera, as has the pneumogastric, 
but may also project into and from other system-centers. The 
lateral columns of the spinal cord, the tegmentum and crura 
cerebri in their main mass may thus be regarded as cerebro- 
spinal nerves of the highest series, having lower system-centers 
for peripheries. The prz-frontal lobes thus exert an inhibitory 
control over the highest centers, because such centers are periph- 
eries for the nerves of these foremost ganglia. 
We accept the motions of protoplasm as evidence of life, and 
yet ungrouped elementary atoms are subject to the play of physi- 
cal forces, which become kuown as modes of motion :, sound, heat, 
light, electricity, etc., through the enanecs# in place of atoms and 
molecules. 
Inasmuch as sensations have for their ultimate expression 
motion in the living organism, cause and effect exchange places 
in the recognition that forces are manifest to us as sensation only 
in the molecular movements caused by forces. These molecular 
movements impress us as sensations which, of necessity, must be 
translated into some form or forms of motion. 
Sensibility and motility, then, are sequentially convertible 
terms, and we find it none the less true in the most complex than 
in the simplest forms of life. : 
There are certain fundamental considerations which should 
stand in axiomatic relation to all biological inquiries. 
Ist. Sensibility and motility are merely afferent and efferent 
terms to express the effects of force upon matter and matter ups 
force, 
2d. In life a primary object of motion is for procurement of 
food. 
3d. Growth depends upon proper nutrition (ingestion). 
4th. Multiplication (as fission) proceeds from growth. 
. Food is any material, gaseous, liquid or solid, which tends 
toward nutrition of the body. 
6th. “‘ Development is a process of differentiation by which the 
primitively, similar parts of the living body become more and 
more unlike one another.” (Von Baer.) 
7th. “ Higher sensory organs are special elaborations with one 
special function capable of response to stimuli of one special kind. 
They are developed from the lower kind of sensory organs, and 
oftentimes still possess the essential structure of that lower kind.” 
(Gegenbaur.) 
