PHYSOSTIGMINE 413 



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 infiuence of the drug upon the nervous 

 [system, and is unimportant from a therapeutical standpoint. 



Nervous Sysiem and Muscles. — The essential physiolo- 

 gical action of physostigmine consists in depressing the cells 

 of the inferior cornua. This has been abundantly and di- 

 rectly proved by application of the alkaloid to the spinal 

 cord. Tlie superior columns are finally depressed; per- 

 ception of pain is wanting, but that of touch persists. The 

 sensory nerves are not affected, and the motor nerve trunks 

 but slightly. The muscular tremors are due to. stimulation 

 of the voluntary muscles themselves, or to the motor nerve 

 endings. These are characteristic of physostigma poisoning 

 in animals, but are not so frequently observed in man. 

 Calabarine may be present in old preparations of physo- 

 stigma, from decomposition of physostigmine, and acts like 

 strychnine on the spinal cord. In poisoning by such, cala- 

 barine may induce convulsions. The involuntary muscles 

 throughout the body are stimulated, including those of the 

 stomach, intestines, bronchial tubes, heart, blood vessels ( ?), 

 spleen, uterus, bladder and iris. In the case of some of these 

 organs, it has not been decided whether the muscles them- 

 selves, or the motor nerve terminations, are affected. 



Respiration.- — The respiration is not disturbed by medi- 

 cinal doses. Toxic quantities at first quicken, and then 



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