222 INORGANIC AGENTS 



arsenic the epidermis peels off very rapidly, owing to 

 degeneration of its lower layers. 



Internal. — Digestive Tract. — Arsenic, when given in 

 minute doses, improves the* appetite, and increases both the 

 motion and secretions of the stomach and duodenum. In 

 larger amounts, arsenic is an irritant, causing loss of appetite, 

 nausea and digestive disturbance. In toxic doses arsenic 

 produces gastro-enteritis. 



Blood. — Arsenic is absorbed into the blood, and in some 

 forms of ansemia increases notably the number of red 

 corpuscles, and to some extent the hsemoglobin. 



Circulation. — It is said that arsenic stimulates the pulse 

 rate when given in minute doses. In large doses it has a 

 local depressing action on the heart — and probably on the 

 vasomotor centre — lowering the force and frequency of the 

 heart and reducing blood pressure. The nerve endings, 

 ganglia, and muscle of the heart are alike paralyzed, and 

 this action takes place when the heart is removed from the 

 bodj'. 



Respiration. — In small doses arsenic quickens the 

 breathing and stimulates the respiratory centre ; whereas in 

 lethal amounts the respiration fails through lowered blood 

 pressure and exhaustion. 



Nervous System. — The nervous apparatus is powerfully 

 influenced by arsenic. Toxic doses cause paralysis of the 

 spinal tracts, in frogs, with loss of sensation, motion, and 

 reflex action, and the brain nerves are also depressed. The 

 nerve trunks are chiefly -affected in the higher animals. 

 There is peripheral neuritis and trophic changes occur. 

 Medicinal doses of arsenic are stimulant to the nervous 

 system generally. 



Metaholism. — Therapeutic doses probably diminish 

 tissue change and the elimination of urea and carbonic 

 dioxide. Large doses, on the other hand, increase metabolic 

 processes and the escape of nitrogenous waste. 



Elimination. — Arsenic is eliminated slowly by most 

 channels, but mainly by the urine and to a less extent 

 by the mucous membrane of the respiratory and di- 

 gestive tracts. Traces are found in the milk, sweat, tears 

 and saliva. It exists in, and can be recovered from, the 



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