Pomona College, Clareinont, California 81 



2. Legs stimulated at center of body. Anal end drew up on tlie side stimulated. 

 This reaction toolf longer on the right side, because the stimulus had to cross at the 

 injury. 



3. From the injury of the nervous system of the muscles, the specimen moved 

 with a swinging motion. It could reverse its movements. 



Experiment IX. About one-third of the brain was removed, the right connective 

 was severed between the brain and the next ganglia, all connections with the eye 

 were severed on the same side. Results: 



1. No co-ordination of leg movement. Legs interfered with one another. 



2. At first, no sense of correct position. As willing to stay on back as normal 

 position. 



3. Most noticeable result was that it reversed movement with apparently as 

 much ease as it went forward. It traveled the length of the dish. This centipede 

 lived twenty-four hours. 



Experiment X. Removed sub and supra ganglia. Results: 



1. Had better co-ordination of leg movement than one with one-third of brain 

 removed (Experiment IX), however, it needed stimulation for movement. A slight 

 jar of the dish was stimulus enough for the reaction. After this experiment the 

 centipede lived sixty hours, thus showing the injury to be less of a shock than in 

 experiment nine. 



Experiment XI. The centipede was cut into nearly equal parts. This last 

 experiment is of a different type but results are along the same line as others. 

 Results: 



1. In tail half there seems to be co-ordinated reaction of legs, suggesting that 

 the symmetry has not been interfered with. It turns toward side stimulated. Tail 

 end remained alive a little over two hours. 



2. The head end was again cut into two parts. The central section was active 

 and remained alive for two hours. The head end was very active. It had initiative 

 to move without being stimulated, which power the other two parts did not have. 

 The head end remained alive three hours. 



GENERAL CONCLUSIONS 



1. The head ganglia seem to be necessary to initiate movements. 



2. The body ganglia are rather independent centers for local control, and 

 complete co-ordination is possible without the head. 



3. The stimuli travel up and down the nervous system, both on the side 

 stimulated and on the opposite side. 



4. In case a connective is served on one side, the stimulus is capable of crossing 

 over to the other side but the reaction is somewhat delayed. 



5. When alternate connectives are severed for some distance, the stmulus, 

 although delayed, passes from one end to the other. The delay is increased according 

 to the number of connectives severed. 



6. Centipedes as compared with millipedes do not as a rule reverse the 

 movements of the legs, but unilateral injuries to the brain seem to permit the reverse 

 movements upon stimulation. 



(Contribution from the Zoological Laboratory of Pomona College.) 



