| 
ACTION OF CHLOROFORM UPON THE HEART AND ARTERIES. 329 
slowing becoming as time proceeds gradually more marked, and the consequent fall of 
blood-pressure lower. But cardiac arrest does not show itself until the influence of the 
atropine has completely passed, and the former conditions can be then restored by a 
similar dose. 
There is no reason to believe that the human subject is less susceptible to the 
influence of atropine than the dog, and the opinion which has been expressed, that an 
enormous dose would be required to abolish the power of the vagus to cause cardiac 
arrest, appears therefore to be erroneous.* 
HAR 
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Fic. 18.—Normal effect, in the dog, of vagus stimulation of moderate strength (coil 100 mm.) with light anesthesia, showing 
the tendency of the heart to escape from the inhibition. This was taken immediately before and from the same dog as 
the (reduced) tracings shown in figs. 12, 13, and 14, but chloroform was administered in the interval, and the tendency to 
inhibition is seen in these to be much more pronounced. 
Since abrupt arrest of the heart and of respirations can be absolutely prevented by 
| prior administration of a small dose of atropine, the conclusion forces itself upon™us 
that the precaution of such administration is one that should never be omitted. 
Atropine cannot, as we shall see, prevent death where a dose of chloroform 
sufficient to produce paralysis of respiration and complete “paralytic dilatation” of 
* See on this subject remarks by H. C. Croucn and T. G. Bropiz in Trans. Soc. Anesth., vol. vi. pp. 70 and 81, 
| 1904. J. Haruey (Brit. Med. Journ., vol. ii., 1868, p. 320) recommended a dose of from ;45 grain to 7 grain in man, 
_ DastRE (Soc. Biol., 1883, p. 242) states that a dose of atropine amounting to 0:0015 gramme (= 7; grain) is sufficient 
for the purpose indicated.. Lantos and Mauranar (Arch. de Phys., 1895, p. 692) recommend the employment; of 
| oxy-sparteine in place of atropine. 
