f 84 Expeiimnils and Olservations on 



former only are concerned in those functions which are 

 directlv necessary to life, and as the alimentary canal is 

 often affected (uily in a slight degree, we must consider the 

 affection of the heart and nervous system as being the im- 

 rnediate cause of death. 



In every experiment which T have made with arsenic, 

 there were evident marks of the influence of the poison 

 on all the organs which have been mentioned ; but they 

 ■were not in all cases affected in the same relative degree. 

 In the dog, the affection of the heart appeared to predomi- 

 nate over that of ihc brain ; and on examining the thorax, 

 immediately after death, this organ was found to have ceased 

 Acting, and in a distended state. In the rabbit, the affec- 

 tion of the brain appeared to predominate over that of the 

 heart, and the latter was usually found acting slowly and 

 feebly, after the functions of the brain had entirely ceased. 

 In the rabbit, the effects of the arsenic on the stomach and 

 intestines were usually less than in carnivorous animals. 



The action of arsenic on the system is less simple than 

 that of the majority of vegetable poisons. As it acts on 

 different organs, it occasions different orders of symptoms; 

 and as the affection of one or another organ predominates, 

 so there is some variety in tho symptoms produced even in 

 individual animals of the same species. 



In animals killed by arsenic, the blood is usually found 

 fluid in the heart and vessels after death ; but otherwise all 

 the morbid appearances met with on dissection are con- 

 fined to the stomach and intestines. As this ii the case, 

 and as the aflii:ction of these organs occasions remarkable 

 symptoms, it may be right to mention the result of my ob- 

 servations on this subject. 



In many cases where death takes place, there is only a 

 very slight degree of inflammation of the alimentary canal : 

 in other cases the inflammation is considerable. It ge- 

 nerally begins very soon after the poison is administered, 

 and appears greater or less according to the time vvhicfi 

 elapses before the animal dies. Under the saiTie circum- 



highly probable, that the heart is aficcted only throu;rh tlie medium of its 

 nerves; but the aflection of tiie heart is so far independent of the affection 

 of the nervous system s;cnerally, that the circulation may cease although 

 the functions of the brain arc not suspended, and tiie functions of the brain 

 may be wholly suspended without the circulation being at all disturbed. In 

 proof of the firn of these propositions, I may refer to my former experiments 

 on theunasantiar,in which the sensibility of the animal continued to she very 

 inscnnt of death ; and respiration, which is under the influence of the brain, 

 continued even after the lieart had ceased to act. In proof of the second, I 

 may refer, amon^ many others, to the experiments detailed in the Croonian 

 Lecture for 1810. 



Stances, 



