ACTION OF ARSENICAL COMPOUNDS 207 



arsenic the epidermis peels off very readily, 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 anaemia increases notably the number of red 

 corpuscles, and to some extent the haemoglobin. 



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 a local 

 action on the vessels — 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 

 body. 



Respiration. — In small doses arsenic stimulates the 

 respiratory centre, and probably the peripheral vagi ; whereas 

 in lethal amounts it is said to paralyze only the latter. 



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. There is conflicting testimony relating to 

 which centres succumb first. The nerve trunks are affected 

 in the higher animals. There is peripheral neuritis and 

 trophic changes occur. Medicinal doses of arsenic are 

 stimulant to the nervous system generally. 



Metabolism. — 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. It is found in the urine, faeces, milk, sweat, tears 

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



