No. 3.] LIMULUS POLYPHEMUS. 445 
(7) In Limulus that had the entire brain, post-oesophageal 
ganglion, and with the exception of three ganglia, the collar 
extirpated, it was found that the three appendages correspond- 
ing to the three ganglia that were left intact, would make the 
proper masticatory movements, and that food placed in its 
mouth was swallowed. The post-mortem, made three weeks 
after the operation, showed that the muscular part around the 
mouth had regenerated. 
To recapitulate :— 
1. Lesion or loss of part or the entire brain, oesophageal 
collar, or post-oesophageal ganglion, has no influence on the 
respiratory movements. 
2. When the abdominal cord is cut anterior to its first 
ganglion the plates are no longer affected by external stimuli 
anterior to the lesion, nor are parts anterior to the injury 
influenced by stimuli on the gill-plates. The gill-plates all 
move in the same rate, extent, and rhythm. 
3. Severing the cord, for example, between the second and 
third ganglia, or extirpating a ganglion, so that there is an 
anterior division connected with the brain and a posterior 
division of the plates separated from it, the rate of respiratory 
movements of both divisions under ordinary conditions is 
practically the same. After the animal is made to exercise, 
after being fed, operated on, or irritated, the rate of the dif- 
ferent divisions is altered, but in like direction. For instance, 
after exercise both divisions of plates inspire at increased rate. 
After feeding or being irritated the rate of both divisions 
increases, but that of the anterior may be more rapid than 
that of the posterior division. In short, the rate of the dif- 
ferent plates is the same when they are stimulated by the 
condition of the blood alone. 
The extent and rhythm of the plates above and below the 
lesion vary according to circumstances. After feeding or 
irritation the anterior gill-plates move in greater extent and 
different rhythm from those posterior to the injury. Cramp 
movements and interrupted respiration that often occur in 
the posterior division, rarely appear in the anterior. 
