442 HYDE. [VoL. IX. 
On the other hand, the regular rate of the plates anterior to 
the lesion, is not in the least altered by the stimulus. If, 
however, parts anterior to the lesion are touched, the append- 
ages strike out in all directions and the anterior plates stop in 
expiratory phase. The posterior division is not interrupted in 
its rhythm, unless the abdominal part exercises a secondary 
influence, by turning ventrally. 
(f) When the cord was cut, both anterior to the first and 
third ganglion (I and III, Fig. 1), both divisions of plates were 
separated from the brain, and, as was said, the first and third 
ganglia were injured by the operation. If one of the plates of 
the posterior division was pressed, both plates stopped a few 
minutes; then began rapid inspiratory movements ; but the 
other plates were not disturbed in their rhythms. 
When the second plate was pressed, it stopped in expiratory 
phase, several seconds, but no other plate was in the slightest 
influenced by the stimulus. 
Pinching either the first or third plate produced no change 
whatever on the animal. Evidently they lost all sensibility. 
Furti:ermore, no annoyance was exhibited, as, for instance, 
by beating about of appendages, if any one of the gill-plates 
was pinched. 
The above observations have demonstrated that stimuli on 
parts posterior to the lesion have no effect on plates anterior 
to it, and vice versa. Each division of plates has its own reflex 
centres. When a ganglion was extirpated or injured, the reflex 
action of its corresponding plate was abolished. 
Therefore, in the performance of the typical reflex actions 
above cited, the ganglia of the cord are the centres. 
To conclude: The centres of respiratory movements, as has 
been shown, are situated in the ganglia of the abdominal cord. 
Their mode of action may be characterized as reflex and auto- 
matic: reflex, inasmuch as it may be temporarily increased or 
diminished by occasional peripheral impulses ; automatic, as it 
seems to go on of itself, being kept going, however, by con- 
tinuous stimuli that reach the respiratory centres, by the blood 
and the nerves. 
If no outside stimulus is exercised, the rate of the plates, 
