154 



Mr. Graham Brown. 



[Nov. 12, 



asphyxia effect is obtained. Towards the end of the second phase the rise 

 becomes much less rapid than at its commencement, and the curve finally 

 becomes again parallel to the abscissa as the maximum effect is reached. 

 The curve of minimum flexion — that joining the lowest points in the beats — 

 may also fall in the first phase. If it does so its fall is less than that of the 

 curve of maximum flexion, and more usually it remains parallel with the 

 abscissa throughout the first phase. At the end of that phase, and when the 

 beats are again increasing in rate of rhythm, this curve commences to rise 

 more rapidly than that of maximum flexion. This rise continues to be more 

 rapid until the maximum asphyxia effect is attained. In fact, both curves 

 continue to rise throughout the phenomenon. That of maximum flexion has 

 a shorter latency and a more gradual rise than the curve of minimum flexion, 

 which has a longer latency and a more rapid rise. In consequence of this the 

 beats are of greatest relative extent (that is, from apex to their lowest point) 

 at the end of the first phase when the curve of minimum flexion is just about 

 to rise, and thenceforward they progressively diminish in extent — at the same 

 time becoming increasingly more rapid. The maximum effect is attained when 

 the curve of minimum flexion coincides with that of maximum flexion. Just 

 before this is attained the beats are very small in extent and very fast. 

 When it is attained they disappear and there is left in their place a state of 

 maintained flexion. This maintained flexion may continue to increase for a 

 short time after this. 



Change in Bilateral Relations. — The temporal relations of the movements 

 in the two hind limbs are of interest during this phenomenon of asphyxia. 

 At the commencement of the condition it may be supposed that the 

 beats in the two hind limbs are accurately alternate. In the first phase 

 of the asphyxia phenomenon, when the beats slow in rate and increase in 

 extent, this relationship persists. Thereafter a change makes its appearance 

 in the relationship of the beats on the two sides of the body. The apex of 

 the beat on one side at this point falls midway between the apices of two 

 beats on the other. In successive beats the apex then leaves the mid-point 

 and either advances or retires towards the first of the two apices of the other 

 limb between which it falls (fig. 5).^ This process is continued until the apex 

 of a beat of one limb actually coincides with that of a beat in the other. 

 The movement is then that of the gallop — synchronous beats in the two 

 hind limbs. This state often persists for the remainder of the period of 

 asphyxia, but sometimes the beats become again less completely synchronous. 



This phenomenon of progression in asphyxia, if it is induced in one of the 

 rare cases in which the progression is already synchronous, may not interfere 

 with that synchronism. The beats may become slightly more fast. 



