blood is neces- 

 sary to life. 



262 ACTION OF rOISONS ON THE ANIMAL SYSTEM. 



Vegetable poi- Some experiments are already before the public, which led 



sons acton the nrig to conclude, that vegetable poisons, when applied to 



through the wounded surfaces, affect the system by passing into the cir- 



blood : culation through the divided veins. From this analogy, and 



from all the circumstances just mentioned, it may be inferred, 



so does arse- that arsenic, in whatever way it is administered, does not pro- 



"'*^* duce its effects even on the stomach until it is carried into the 



blood. 



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



constant supply of it is necessary for the maintenance of the 



functions of the vital organs. The next object of inquiry 



therefore is, when arsenic has entered the circulation, on what 



organs does it operate, so as to occasion death ? 



Arsenic causes When arsenic is applied to an ulcerated surface, it produces 



asac;'ufstic"°^ ^ slough, not by acting chemically, like caustics in general, 



but by killing but by destroying the vitality of the part to which it is applied, 



t e part. independently of chemical action. This led me at first to 



suppose, that, when arsenic has passed into the circulation, 



death is the consequence, not so much of the poison disturb- 



Acting as a ing the functions of any particular organ, as of its destroying 



poison, it does at once the vitality of every part of the system. The foUow- 

 jjot destroy . . • ■' '^ ...... 



the life of i"g Circumstances, however, seem to show, that this opinion 



every part at 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 quantify 3 and the muscles are capable of being ex- 

 cited, after death, to distinct and powerful contractions by 

 means of the Voltaic battery. 

 Exp. 3. Arse- Experiment 3. Seven grains of the white oxide of arsenic 

 nic applied to ^gj-^ applied to a wound in the back of a rabbit, 

 a wound in a , ^V , , • , , , • • 



jzbbit. -i" a few mmutes he was languid, and the respirations were 



small and frequent. The pulse was feeble, and after a little 

 time could not be felt. The hind legs became paralysed*. 



He 



poison does not produce its fatal -effects until it has entered the circula- 

 tion. I have to regret, that I have had no opportunity of seeir.g the 

 original of this diasertatioii, ' 

 The influfuce * I have observed, tiiat, where the functions of the brain are disturbed} 

 of the brain paralysis first takes place in the muscles of the hind legs-; afterward in 

 less easily con- tJ;ose of the trunk and fore legs; aud list of all in the muscles of the 



■•- , ■ ' «ars 



