162 . - REPORT— 1871. 



the capillaries were left empty, the venous current ceased, and the condition 

 of temporary suspension of all circulation, except slo-wly, in the arterial 

 supervened. The effects here named were well marked firom the action of 

 the chlorides ; they were seen under the influence of bichloride of methy- 

 lene, they were still more definite under chloroform. 



To sum up, if my observations be correct, the action on the systemic circula- 

 tion of the narcotic vapours named was seen to be primarily on the venous cur- 

 rent or, I should more correctly say, was primarily manifested in the retar- 

 dation of the venous current, secondly in the capillary, and finally in the 

 arterial current. During recovery, moreover, the return of a steady onward 

 current was manifested in the veins before it was restored in the capillary- 

 channels. This order of events coincides purely with the order of pheno- 

 mena of death under the influence of narcotic vapours, as observed both in 

 man and the lower animals. It is, I think, the invariable fact that the right 

 side of the heart in such fatal cases is the first to cease its action, and in 

 animals, when the heart is exposed to the air soon after the death, the right 

 side is the first to recommence action. From these facts the inference, I 

 think, is clear that the arrest of the circulation begins, during the narcotism, 

 in the retardation of the venous current, secondly in the capUlary, and 

 lastly in the arterial current. 



The course of recovery, when recovery takes place, appears to be preceded 

 by some act of relief to the venous column of blood. The motion that re- 

 mains in the arteries is not the fu-st to increase, the circulation through the 

 capillary is not first manifested ; that which happens, as a distinct sign of 

 recovery, is a movement onward by the veins ; as this movement improves 

 the movement through the arteries improves, the capillary vessels refill, and 

 the circuit of the minute circulation is steadily and perfectly restored. 



Prom these observations on the minute systemic circulation when the 

 body is under the influence of a narcotic vapour of the irritant class, I infer 

 that the changes of circulation observed do not proceed immediately from an 

 action exerted by the narcotic vapour upon the extreme systemic vessels, but 

 form an obstruction commencing on the venous side, and in the lesser or 

 pulmonary circulation. When a warm-blooded animal is suddenly killed by 

 a large dose of the vapour of chloroform, the lungs are invariably found 

 blanched, the light side of the heart engorged with blood, and the left side 

 empty of blood. We see in these conditions that of necessity, in the extreme 

 parts of the systemic circulation of the animal, there has been retardation of 

 the blood through the veins ; and we may iofer on the fairest, nay completest, 

 evidence that the return of motion, which is seen commencing in the veins in 

 the systemic circuit, is due to a returning current in the breathing-organs ; 

 in other words, the renewal of the active life of the animal recommences in 

 passive breathing. The same order of phenomena happens, precisely, during 

 the recovery of a warm-blooded animal, after apparent death from chloro- 

 form, under the influence of artificial respiration ; for so soon as the animal 

 recommences to breathe, however faintly, its return to life is seciu'ed. 



The position then assumed, that the primary arrest of the column of blood 

 during fatal narcotism is in the lesser circulation, we have to ask whether the 

 arrest commences in the heart or in the lungs. The commonly accepted 

 view has been that it commences in failure of the right side of the heart ; 

 but I incline to think that this view is incorrect, and that the positive source 

 of failure is in the peripheral circulation of the lung. The vapour inhaled 

 impresses, I think, immediaiehj the minute circulation, and acts not by 

 absorption into the blood, but by simple and instant contact with the minute 



