1912.] 



" Narcosis Progression " in Mammals. 



151 



muscles of the other save only the two retained had no apparent effect upon 

 the rate of rhythm of the movements. 



The general appearance of this tracing was such that to inspection it 

 might easily be mistaken for one in which the movements of the intact hind 

 limb were recorded. 



RIGHT 



C.E. RATHER uEEP MARKED ASPMYJTIA 



Fig. 3.— Experiment C, LXII, record 110 ; 19.7.11.— Normal cat, narcosis progression under the 

 influence of chloroform-ether narcosis reinforced by the application of 0"2 grm. " novocain.' 1 

 Effect of asphyxia — trachea closed 1-2 seconds before ordinates 1. In the left limb the beats 

 are seen for a time to continue to relax to the same level but to become of increased extent 

 and rate of rhythm. Then the relaxation becomes less complete, and as this becomes still 

 less the beats decrease in extent, although their height does not fall. In the left limb the 

 beats do not disappear, but in the right they disappear and a state of maintained flexion is 

 left. In the left limb the pauses between the beats are seen to disappear. " The beats in the 

 two limbs are at first alternate (as at ordinates 1, 2, 3), but when they are of maximum 

 extent in the left limb they are very nearly synchronous. Later they are again alternate. 



VIII. Narcosis Progression in Cats : the Effect of Asphyxia. 



In the cat under narcosis the effect of asphyxia may easily be studied by 

 completely closing the elastic trachea (or by closing a tracheal cannula when 

 that has been inserted). In these experiments this complete closure was 

 applied for short periods — about 15 seconds to about 50 seconds (maximum). 

 An asphyxia of about 30 seconds is sufficient to give the effects to be 

 described. These have been examined both in the intact hind limbs and in 

 the individual antagonists at the ankle. The records demonstrate many 

 minor variations in the phenomenon. The description here is that of the 

 typical effect. 



