PHYSIOLOGY OF NERVOUS SYSTEM IN ARTHROPODS. 477 
and ventral surfaces of the ventral chain in Crustaceans ; and 
Yung says, ‘ The classical opinion that the inferior surface is 
sensitive and the superior motor is invalidated by my experi- 
ments. The nerve-roots are at the same time both motor and 
sensory.’ As no attempt, however, was made by the authors 
quoted to eliminate reflexes, it is difficult to understand how they 
could conclude, from the fact that movements occur by stimula- 
tion of a given tract, that the function of the tract is motor. 
On the other hand, Faivre [171] asserts that by destruction 
of small portions of the dorsal or ventral surfaces of the 
ganglia in Dytiscus he was able to produce either motor 
paralysis or anesthesia, and proved that the dorsal surface is 
motor and the ventral sensory in function; but he insists that 
these results can only be obtained when the lesions are super- 
ficial, destruction of the white core gives rise to ambiguous or 
contradictory results. 
Faivre arrived at the following conclusions : 
a. Sensibility and excitability are distinctly located. The 
inferior surface of the ganglia is the special seat for afferent 
and the superior for efferent (motor) impulses. 
b. Paralysis (motor) results, from superficial lesions of the 
superior surfaces of the pro- and mesothoracic ganglia, in the 
foot and leg of the same side. 
c. By operating on the infero-lateral aspect of these ganglia 
sensory impulses, propagated from the corresponding leg, pro- 
duce no result, but the power of movement remains intact. 
d. A double paralysis of sensation and motion may be pro- 
duced by appropriate superficial lesions without impairment 
of the conductive power of the ventral cord to, or from, the 
ganglia behind the lesion. 
e. Paralysis (motor) is more easily produced singly, 7.e., 
without corresponding anesthesia, than anesthesia without 
motor paralysis. 
6. The ganglionic chain in the Myriopoda (Newport*) con- 
* Newport, G., ‘On the Structure, Relations, and Development of the 
Nervous and Circulatory Systems in Myriopoda and Macrourous Arachnida.’ 
Phil. Trans., 1843. Part ii. 
