2S2 Kxperimenls a^nl Ohservatmis on 



which led me to conclude that vegetable poisons, when ap- 

 plied to wnnndfd suriaces, affect the system by ]);tssiiio: into 

 the circulation through the divided veins. From thus ana- 

 logy, and from all the circumstances just nietitioned, it 

 may be interred that arsenic, in whatever way it is admi- 

 nistered, does not produce its effects even on the stoniacli 

 until it is carried into the blood. 



But the blood is not necessary to life, except so far as a 

 constant supply of it is necessary for the mainicnar.c^ of the 

 functions of the vital organs. The next object 6t inquiry 

 therefore is, when arsenic has entered the circulation, on 

 w hat origans does it operate, so as to occasion death ? 



When arsenic is applied to an ulcerated surfdce, it pro- 

 duces a slough, not by acting chemically, l;ke caustics in 

 general, but by destroying the vitality of the part to which 

 It is applied, independently of chemical action. 'I'his led 

 me at first to suppose, that when arsenic has passed into 

 the circulation, death is the consequence, not so much of 

 the poison disturbing the functions of any particular organ, 

 as of its destroying at once the vitality of every part of the 

 system. The following circumstances, however, seem to 

 show that this opinitm is erroneous. In an animal under 

 the full influence of arsenic, even to the instant of death, 

 some of the secretions, as those of the kidneys, stomach, 

 and intestines, continue to take place in large quantity ; 

 and the muscles are capable of being excited, after deatli, 

 to distinct and powerful contractions ty means of the Vol- 

 taic battery. 



Experhnent 3. — Seven grains of the while oxide of 

 arsenic were applied to a wound in the back of a rabbit. 



In a few minutes he was languid, and the respirations 

 were small and frequent. The pulse was feeble, and alter 

 a little time could not be felt. The hind legs becair.e pa- 

 ralysed*. He grew insensiiile, and lay motionless, but 

 with occasional convulsions. At the end of fifiy-three 

 minutes from the time of the arsenic being applied, he was 

 apparerillv dead ; but on opening the thorax, the heart was 

 found still acting, though very slowly and feebly. A tube 

 was introduced into the trachea, and the lungs were artifi- 



• I have observed, thSt where the funciioiis of the braiu are disturbed* 

 paralysis first takes place in the muscles of the hind legs; afterwards in those 

 of the trunk and fore leg^ ; i'.;;c! last of all in the muscles ot the cars and 

 face. Thrse fasts seem to show that the iiiiluence of the lirain, like that of 

 the heart, is not prop:igatcd with the same facility to the distar.t as to the 

 near organs; and this is furtlier confirmed liy cases of disease which occa- 

 sionally occur, in which, although the paralysis is confined to the lower half 

 of the body, the morbid appearances met with on dissection are entirely 

 coufined to the brain. 



cially 



