20 VETEKINAEY TOXICOLOGY 



are the protoplasmic poisons, such as mercuric chloride, 

 phenol, and hydrocyanic acid. 



Among irritants are included typically the salts of the 

 heavy metals, but it will be remembered that to an irritant 

 effect may often be added nervous effects, leading to the 

 designation of narcoto-irritant applied in practice to so many 

 vegetable poisons. And similarly with the metals there 

 must be distinguished the local irritant effects and the 

 general effects produced after absorption. 



Non-irritant nervous poisons may be distinguished ac- 

 cording to the centre acted upon. Local effects are not 

 significant, and only after absorption do symptoms set in. , 



A fairly complete survey of poisons, arranged according 

 to their physiological effects, is that of Eabuteau : 



Haematic, acting on blood corpuscles : Cyanides, phos- 

 phorus, arsenic, alcohol, carbon monoxide, sul- 

 phuretted hydrogen. 



Haematic, acting on plasma : Silver. 



Neurotic, paralyso-motor : Curarine, aconitine, conine, 

 cicutoxin. 



Neurotic, spinal : Strychnine, cantharidin. 



Neurotic, cerebro-spinal : Chloroform, ether, morphine. 



Muscular : Solanacese, digitalis, veratrine, antimony, 

 potassium, copper, lead, mercury, zinc* 



The chemical classification depends on the most con- 

 venient routine followed in an analysis. 



For analytical purposes we class poisons as follows : 



(a) Volatile poisons — i.e., those which may be distilled 



either from an alkaline or acid solution, com- 

 prising phosphorus, hydrocyanic acid, carbolic 

 acid and its allies, essential oils, alcohol, chloro- 

 form, ammonia, conine, and nicotine. 



(b) Metals and metalloids : Lead, mercury, arsenic, 



antimony, copper, zinc, chromium. 



* According to more recent opinion, it is doubtful whether the 

 metals should be included in this section. 



