STIMULANTS OF MOTOR CENTRES 505 



They stimulate the medulla with the respiratory, cardiac, 

 and vaso-motor centres, and hence increase the rapidity 

 and depth of the respirations, the number and force of the 

 pulsations and raise blood-pressure, although the heart itself 

 may be somewhat slowed by vagal inhibition. Larger doses 

 cause muscular twitching, hypersesthesia, greater acuteness 

 of the special senses, and clonic convulsions. The extensor 

 muscles usually overcome the flexor muscles, producing 

 opisthotonos. Death results from asphyxia, occurring 

 during a spasm, or from paralysis and collapse, occurring 

 during a period of relaxation. Strychnine is absorbed 

 rapidly from the small intestine and rectum, and still more 

 rapidly from the bronchi and cellular tissues. It has been 

 detected in the spinal cord, brain, liver, spleen, and blood. 

 It is tardily excreted unchanged, or as strychnic acid, in the 

 urine, in which it has been found an hour after administra- 

 tion, and has also been detected forty-eight hours later. 

 Owing to its slow elimination strychnine should be regarded 

 as a cumulative medicine. 



Toxic ACTIONS. Poisonous doses within a few minutes 

 produce in all animals trembling and twitching of voluntary 

 and also of involuntary muscles, and violent spasms, usually 

 lasting one to two minutes, gradually becoming more fre- 

 quent and severe ; the glottis, diaphragm and other muscles 

 of respiration being involved, death is caused by asphyxia. 

 The symptoms (and mode of death) resemble those of 

 tetanus, but are suddenly developed, intermittent, and more 

 rapidly fatal. The temperature is raised sometimes two 

 degrees. 



The several classes of animals differ in their susceptibility 

 to the actions of strychnine. Horses and cattle are not 

 so readily affected as men and dogs. Poultry are said to 

 be less easily affected than other birds ; while guinea-pigs 

 and some monkeys seem quite insusceptible to its action, 

 at least so long as it is given by the mouth (Wood). 



Horses after swallowing six grains of strychnine had 

 twitching of the muscles, and were poisoned by twelve 

 grains in about twelve minutes (Tabourin). Five grains 

 in bolus produced, after six hours, abdominal pain, laboured 

 breathing, acceleration of the pulse from 42 to 60, excite- 



