1912.] " Narcosis Progression" in Mammals. 



143 



by means of the subcutaneous injection of " novocain " (0"l-0'2 grm.), it 

 was found that movements of progression occurred, and that scratching 

 could not be obtained. This accidental discovery was confirmed in other 

 cases, and it must appear that the application of this drug causes the narcosis 

 movements of the guinea-pig to change from those of the scratch to those 

 of progression. This result is not conditioned by the site of the application 

 of the drug, for it is obtained after intra-peritoneal injection. In cats in 

 which narcosis progression has not occurred, an injection of " novocain " may 

 sometimes be followed by their appearance. 



When these movements occur in the guinea-pig they are bilaterally 

 alternate in the two hind limbs. Their amplitude may be greatly increased 

 during the application of a peripheral stimulus. Such an augmentation, 

 for instance, occurs if mechanical pressure be applied to the fold of skin 

 which passes from the abdomen to the front of the thigh. In this case the 

 amplitude of the " beats " is increased in the limb of the same side and 

 diminished in that of the opposite side. 



The usual rate of rhythm of the movements is about 20 beats per 

 second in each hind limb (two complete cycles of progression per second). 

 This has been remarkably regular. In one and the same individual variations 

 of rate of rhythm between the extremes of 1'75 and 3 - beats per second 

 have, however, been observed. 



In this same individual the movements of the narcosis scratch were 

 recorded on another occasion. The rate of rhythm of the beats of the 

 scratch varied between 7'0 and 8 - beats per second. This rate corresponds 

 very closely with the average rate of 7*5 beats per second obtained from a 

 large number of different individuals.* It seems to bear the simple 

 relationship of 4 : 1 to the rate of the movements of progression in the same 

 individual. If this is the case it is of interest that the relationship should 

 be 2 : 1 in the case of the rabbitf (where the progression is that of hopping), 

 and of 4 : 1 in the guinea-pig (where the progression is that of running). 



IV. Narcosis Progression in Cats : Intact Hind Limbs, Bilateral Progression. 



The movements in the intact hind limbs, as studied at the ankle, are of 

 flexion followed by extension — rhythmically repeated. Perhaps it would 

 be more correct to say that the movements are of flexion followed by 

 relaxation of flexion — because palpation of the extensors usually fails to 

 detect any movement. There is probably a reciprocal relaxation during 



* ' Quart. Journ. Exper. Physiol.,' 1910, vol. 3, p. 21. 

 t Ibid., 1911, vol. 2, p. 151. 



