1912.] " Narcosis Progression" in Mammals. 



163 



also outlast removal of the lumbar cord of the opposite side of the body. 

 The movements of narcosis progression have also been observed in a pair 

 of antagonistic muscles at the ankle-joint after the motor paralysis of all 

 the other muscles of both hind limbs. Immediately after the de-afferentation 

 of one hind limb (by rapid division of the posterior spinal roots) the move- 

 ments of narcosis progression have been found to be present in the normal 

 hind limb, but have not then been present in the de-afferented limb. 



11. When examined in a pair of individual antagonists at the ankle joint 

 the movements of narcosis progression are found to be confined to the 

 flexor, and then exactly to resemble the movements at the ankle examined 

 in the intact limb. 



12. Asphyxia produced by the complete closure of the trachea for a short 

 period of time (15-40 seconds) produces a change in the movements. This 

 is the same when examined either in the intact hind limb or in the 

 individual flexor at the ankle. The flexor beats at first increase in extent 

 and at the same time slow in rate of rhythm. They may sometimes be 

 decreased in extent for a short time, and may even completely disappear. 

 This phenomenon forms the first phase. When the beats have attained 

 a maximum (after reappearance if they have previously disappeared) they 

 commence to become quicker, and although they still continue to increase in 

 height their relaxation is less complete than before, and their extent 

 decreases. In this second phase of the asphyxia phenomenon there appears 

 to be an increasing factor of maintained flexion. The beats become still 

 more rapid and still smaller until they finally disappear. There is then left 

 a state of marked maintained flexion (flexor contraction as seen in the flexor 

 muscle). 



13. If the movement in the two hind limbs is alternate at the point of 

 commencement of asphyxia this alternation may change to synchronism as 

 the beats become more rapid. This change is a gradual one. The apices of 

 the beats in one hind limb gradually advance in temporal relationship to the 

 apices of the beats in the other from the mid-point between these apices. 

 This advance proceeds gradually until the apex of a beat in one limb 

 synchronises with that of a beat in the other. 



14. If the asphyxia be terminated at the point at which the beats 

 disappear and a state of maintained flexion is left that state of maintained 

 flexion may persist for a few or for many seconds, and may then be broken 

 by the reappearance of beats. These then are fast and small, but become 

 slower and larger in the reverse order to that which obtained during the 

 establishment of the full asphyxia effect. 



15. In narcosis progression the rate of rhythm is usually one of between 



