162 



Mr. Graham Brown. 



[Nov. 12, 



X. Summary. 



1. Movements which seem exactly to resemble those of progression occur 

 in some animals when subjected to general chemical narcosis. 



2. In the rabbit these movements are synchronous in sense of direction in 

 the two hind limbs. This corresponds with the normal hopping type oi, 

 progression in these animals. 



3. In the guinea-pig the movements which normally occur in narcosis 

 are those of the scratch. If, however, the chemical narcosis be combined 

 with novocain the resultant movements are those of progression. They are 

 alternate in the two hind limbs, and thus resemble the movements of 

 ordinary progression in the guinea-pig. 



4. In the cat the movements which occur in narcosis are those of 

 progression. 



5. If the movements be examined in the two hind limbs they are found 

 usually to be alternate. Rarely they are synchronous under normal circum- 

 stances — narcosis gallop. 



6. If the depth of narcosis be gradually increased the movements of 

 narcosis progression gradually fade out. If the depth of narcosis be decreased 

 the movements progressively increase and then suddenly cease. 



7. In either hind limb the movements — as examined at the ankle joint — 

 consist of flexion succeeded by relaxation of flexion (extension), and with a 

 pause in the posture of minimum flexion. Palpation of the tendons at the 

 ankle shows that the flexors are active in this movement. It fails to 

 demonstrate any extensor movement in the intervals of flexor contraction. 

 This may, however, perhaps be present in the phenomenon. 



8. The pauses may be long — of greater duration than the flexor beats — 

 or they may be absent. In the latter case beat succeeds beat without 

 intermission. 



9. Occasionally in a record the movements may fail in one hind limb. It 

 is then found that there is usually an exaggeration of the movements in the 

 other. The beats become of greater extent and quicker than before. This 

 augmentation gradually disappears if the beats in the other hind limb 

 reappear. These, then, are at first smaller than usual, but soon attain their 

 normal extent. 



10. The phenomenon when present has been observed to continue after 

 decerebration. In the lumbar centres it may also outlast rapid division of 

 the spinal cord in the lower thoracic region. In the lumbar flexor centres 

 it may also outlast a removal of the spinal cord aboral from them — in which 

 the ankle extensor centres are cut off. The progression at one ankle may 



