THE FREQUENCY OF THE PULSE. 51 
In 10 seconds. In 10 seconds. 
43°25 42° 
44° 
45° 
43°5 
43°9 
43° 
42- 
43° 
SERShRE 
Experiment VII. A rabbit under the influence of 15 grains of 
chloral— 
When pressure 48 inches. Pulse 136 in a minute. 
” 43 » » 133 » 
” 28 » ” 127 ” 
” 17 ” » 1382 ” 
” 28 ” » 133 ” 
» 24 » 158 ” 
» 19 » » 144 ” 
” rt » 133 ” 
” “75 ” » 136 ” 
, ” 9 »” ”» 127 2? 
death from loss of blood. 
From these experiments it is evident that the pulse does not in- 
crease in frequency with loss of blood, as it did not do so in any one of 
them. 
‘ In Experiment IV the pulse-rate rose on making the incision in Page 11. 
____ the skin necessary to expose the jugular vein, and continued to do so 
q shortly after bleeding commenced, but soon diminished; and after 
‘reaching 36 a minute, remained perfectly constant, notwithstanding a 
- continuous and considerable loss of blood from the vein until the. 
animal was almost exsanguinated. . 
zn With the rabbits the difficulty in keeping them completely under 
= the influence of the hypnotic, with the tendency to struggle, makes 
__ the results less uniform; but in all the cases there was a fall in pulse- 
rate, not a rise, accompanying the reduction in blood pressure. This 
fall, which was not very great, may result from the cooling of the 
_ surface, consequent on. the lessened circulation. 
__- From these observations it may be concluded that variations in the 
amount of blood in circulation do not vary the rapidity of the pulse, 
_ and consequently, that the pulse-rate is not dependent on the blood 
pressure as Marey supposed. 
The next question was—What law as to the frequency of the 
heart’s beats would satisfy these two aboye-proved facts, namely, the 
dependence of the pulse length on the arterial resistance and its non- 
dependence on arterial blood pressure ? ; 
The method adopted by Mr. Fleeming Jenkin for detecting the 
E2 
