146 



Mr. Graham Brown. 



[Nov, 12, 



beat. The apex of a beat at one ankle is then found to correspond in time 

 with the point of transition from beat to beat at the other. 



Where the movements of narcosis progression are fast it may happen that 

 they are no longer bilaterally alternate at the two ankles, but are more or 

 less exactly synchronous. The progression is then that of the gallop. 



The rate of rhythm in different experiments has been found to vary 

 between comparatively wide limits. Thus a rate as slow as 0'6 cycle per 

 second has been registered. (A cycle may be measured by taking the 

 average duration of time between successive apices of the beats at one 

 ankle.) Eates as fast as 2 - 5 cycles per second have been registered under 

 normal conditions ; while under asphyxia in addition to the narcosis the rate 

 has been found to rise as high as 3"3 beats per second — or even higher. 



Even in one and the same individual the rate may vary considerably. 

 Thus on two successive days in one individual rates of 06 and 2 cycles per 

 second have been registered. Nine days later the rhythm was 1 cycle 

 per second. 



The movements are not always regular. Sometimes " grouping " may 

 occur. The beats may then occur in pairs with shorter pauses between the 

 elements of a pair than between successive pairs. Other variations may 

 occur, and sometimes there may be a dropping out of the movements of 

 a limb for short intervals of time during the registration of a long record. 



V. Narcosis Progression in Cats : Intact Hind Limbs, Unilateral Progression. 



Unilateral progression as regards the pair of hind (or of fore) limbs is of 

 course a phenomenon often seen in the case of the mammal which uses 

 quadrupedal progression. Three-leg progression in the dog after injury to 

 one limb is a common sight. It occasionally happens that the phenomena of 

 narcosis progression are entirely confined to one hind limb ; while it more 

 often happens that for short periods of time a bilateral progression in the 

 hind limbs becomes unilateral. 



In the forms of unilateral progression in which the phenomenon is 

 entirely confined to one of the pair of hind limbs there is little to describe. 

 The rate of the movements is almost always very fast, and corresponds to 

 that which obtains in bilateral progression when the movements are 

 synchronous in the two limbs (galloping). 



Temporary abolition of the movements of progression in one limb of the 

 pair may take place during long records of bilaterally alternate movements 

 (fig- 2). 



This abolition occurs suddenly. The beats in one limb fail, and there 

 ensues a shorter or a longer pause during which the beats occur alone in the 



