igoo-i.] Observations on Blood Pressure. 199 



The Effect of Certain Drugs on the Blood Pressure. 



Morphia. — Morphia was used hypodermically upon about forty-five 

 dogs. It was followed in every case by salivation, in the majority of 

 instances by vomiting and in a few by purging. The action of this drug 

 on dogs appears to be very much like that of Apomorphine on man 

 in these respects. Morphia produced distinct slowing of the pulse, 

 and made the animal go under chloroform more easily and stay 

 unconscious longer, and this entirely coincides with what many clinicians 

 have observed. 



Chloroform. — This anaesthetic was always administered on a towel, 

 and no attempt was made to measure the dose. In none of the dogs 

 did vomiting occur after the administration of chloroform had been 

 commenced even when they had had morphia previously, and I find no 

 mention of this complication occurring during the anaesthesia of these 

 animals in any literature. 



In all of fifty-two dogs killed by chloroform the respiration distinctly 

 stopped before the heart. The period between the stoppage of the 

 respiration and the cessation of the heart's action varied from a few 

 seconds to several minutes. As a rule, the more concentrated the chloro- 

 form vapour was, the shorter this period became. In nearly all cases 

 the respiration stopped before the pulse tracing had disappeared, but on 

 several occasions, when it seemed as if the heart had ceased, auscultation 

 showed that it was still beating. After the respiration had stopped the 

 first sound of the heart would get weaker and weaker and at last cease, 

 while the second sound would remain loud and clear for some time and 

 then gradually also cease. The question as to whether the respiration 

 or the heart stops first in chloroform poisoning is one about which a 

 great deal of controversy has raged, and the point is not yet unani- 

 mously settled. The Hyderabad Commission held that the respiration 

 always stopped first, and that there was no such thing as chloroform 

 syncope.' Dr. A. R. Cushny performed many careful experiments with 

 different dilutions of chloroform to see the effect on the heart. If the 

 vapour was very concentrated the heart was affected, but he says, 

 " Although I cannot agree with the Hyderabad Commission that the 

 heart always continues to beat after the respiration ceases, yet the 

 difficulty of maintaining the concentration necessary to paralyze the 

 heart simultaneously with the respiration is extremely great, and I 



I Lieut.-Col. Lawrie, Lancet, March i4tli, 1891. 



