142 



Mr. Graham Brown. 



[Nov. 12, 



Of the three chief joints of the hind limbs the ankle joint is that at which 

 the movements of narcosis progression in the cat are best seen. Where the 

 phenomenon is well marked it may appear at all three joints ; intermediate 

 grades may be characterised by movement at knee and ankle ; where slight, 

 movement only at the ankle may be observed. Even where there is no 

 obvious movement there it is sometimes possible to feel rhythmic " beats " 

 of tibialis anticus by palpation of its tendon of insertion in front of the ankle. 



Although these movements of narcosis progression must have been 

 observed in the cat by many previous investigators, to the best of my 

 knowledge they have not before been minutely examined and described. 

 They are of interest on account of the light which they throw upon the 

 phenomenon of progression in comparison with the various other rhythmic 

 phenomena which may be observed. Such rhythmic phenomena may be 

 seen in the scratch reflex, in simple reflexes, in compounded reflexes, as 

 reflex' rebound, in response to central stimulation of the cut surface of the 

 spinal cord, in the progression phenomenon which may follow a rapid 

 division of the spinal cord, and in the narcosis movements here described. 

 In some experiments several of these forms of rhythmic phenomena have 

 been obtained. 



II. Methods Employed. 



In the guinea-pig the movements of the intact hind limbs have been registered upon 

 the moving surface of the kymograph through the mediation of a pair of levers, which 

 were connected to the hind limbs by means of threads. During the taking of a record 

 the animal was laid upon its back, being sustained with its long axis parallel to the table 

 upon which it rested. 



When the movements of narcosis progression in the intact hind limbs of the cat were 

 registered, the animal was placed prone upon the table. A hot-water bottle was placed 

 under the lower part of the abdomen and had the effect of raising the pelvis. A steel bar 

 (parallel to the table at a distance of about 5 cm. and at right angles to the threads 

 connecting the toes to the recording levers) was placed under the ankles. The movements 

 then registered were almost only those at the two ankle joints. 



The. movements at the ankles have been observed after various operative procedures. 

 Thus they have been examined after decerebration of the animal by rapid division of the 

 brain stem through the anterior colliculi ; after rapid division of the spinal cord in the 

 region of the lower thoracic segments ; after de-afferentation of one hind limb by 

 the division of the posterior spinal roots proper to it ; after motor paralysis of groups 

 of muscles in the two hind limbs ; and, finally, in two individual muscles {gastrocnemius 

 and tibialis anticus — antagonists at the ankle joint) after motor paralysis of all the other 

 muscles of both hind limbs. 



III. Narcosis Progression in Guinea-Pigs. 



In the normal condition under narcosis the rhythmic movements which 

 occur are those of the scratch. On an attempt being made to induce these 

 after local anaesthesia of the receptive skin fields for the scratch-reflex 



