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Mr. Graham Brown. 



[Nov. 12, 



A short period of complete asphyxia produces three kinds of effect upon 

 movements of narcosis progression then in being. These are : Change in the 

 rate of rhythm of the beats ; change in the extent of the beats ; and change 

 in the mutual relations of the beats in the two limbs. 



Change in Rate of Rhythm. — Two main phases occur between the com- 

 mencement of asphyxia and the attainment of its complete effect. The first 

 of these is a slowing of the rate of rhythm. This may be absent, or it may 

 be so great as to cause complete cessation of the beats. It seems to be 

 conditioned by an increase in the pauses between the beats. In extent 

 of duration it is usually slight ; a rate of rhythm before closure of the 

 trachea of about 13 cycles per second may become one of about 1 cycle. 

 This phase lasts for about 9-12 seconds, at the end of which time the rate 

 of rhythm again increases (or the beats reappear if they have been 

 suppressed). The phase of the increase of rate of rhythm is the second. It 

 is never absent unless the beats at the commencement of asphyxia are 

 already very fast. The rate of rhythm becomes progressively more fast, 

 at first by a reduction of the pauses between beats, but later (when the 

 pauses have disappeared) by a reduction of the duration of the beats. This 

 phase may last for as long as 20 seconds, and the rate of rhythm may 

 become thrice that which obtained before the application of asphyxia. Thus 

 a rate before asphyxia of 1*3 cycles per second has been observed to change 

 to one of 3 cycles per second 25 seconds after closure of the trachea ; and 

 one of 1 cycle has changed to 2 - 75. The beats themselves may shrink in 

 duration to 0'75 of the duration before asphyxia. 



Change in Extent. — Synchronously with these changes in rate of rhythm, 

 ■changes in the extent of the beats may appear. This change may be measured 

 either by the examination of the heights of the beats (that is, of the heights of 

 the apices of maximum flexion) ; or by an examination of their lengths (that 

 is, of the distances between the apices and the lowest points in the beats). If 

 the apices of the beats in an asphyxia record be joined by an imaginary 

 line, and if the lowest points be joined all together by another, the beats will 

 appear as conditioned in height at any one point by the distance between 

 the two curves there. The first curve — which is that of maximum flexion — 

 is parallel with the abscissa at the time of the application of the asphyxia. 

 It then sometimes slightly falls (the fall may, of course, be great — as when 

 the beats disappear in the first phase). This fall is soon succeeded by a 

 gradual rise of the curve, and it is most common for this gradual rise to 

 commence at once and without preceding fall. Throughout the phase in 

 which the rhythm slows the curve of maximum flexion gradually rises, and it 

 continues to rise throughout the whole phenomenon until the complete 



