390 VEGETABLE DRUGS 



Dosc—n., gr.i.-iss. (.06-.09) ; C, gr.i.-iii. (.06-18) ; D., 

 gr.Tk-gr.A (.0006-002). 



Given usually iutratracheally or subcutaneously to 

 horses. 



PHYSOSTIGMINE. 



Action Internal. — Alimentary Tract. — The flow of saliva 

 is at first stimulated, whether by direct excitation of the 

 salivary cells or not, is undetermined. Salivation ceases 

 when the gland is deprived of blood by general vascular con- 

 traction. The peristaltic action of the stomach and bowels 

 is increased by the direct local action of the alkaloid on the 

 muscles or ganglia of their walls. There are three stages, in 

 reference to this action, observed in poisoning. First there is 

 stimulation of peristaltic action, then tetanic contraction and 

 diminution of the intestinal calibre, and finally relaxation 

 and dilatation of the bowels. The secretions in the digestive 

 tract are probably augmented. When the alkaloid is given 

 to horses, under the skin, or within the trachea, defsecation 

 and expulsion of gas commonly occurs in the space of an 

 hour, occasionally in a few minutes, and is often consider- 

 able in amount. 



Circulation. — Eserine is readily absorbed, but exerts no 

 influence on the blood. Moderate doses render the cardiac 

 pulsations slower and more forcible, and increase vascular 

 tension. Large toxic doses cause the heart to beat more 

 rapidly and less forcibly. The first effect is due probably 

 to stimulation of the peripheral vagi and heart muscle, and 

 possibly the involuntary muscular fibres in the vessel walls. 

 The second phenomenon follows depression of the heart and 

 peripheral vagi, and terminates in cardiac paralysis and 

 diastolic arrest. The action on the circulation is entirely 

 subordinate to the influence of the drug upon the nervous 

 system, and is unimportant from a therapeutical stand- 

 point. 



Nervous System and Muscles. — The essential physiologi- 

 cal action of physostigmine consists in depressing the cells 



