59 



flex act. But why is there a tetanic contraction instead of the 

 regular reflex movements ? The reason is that the reflex faculty 

 is considerably increased. This will be proved in a moment. 



Before giving this demonstration, I must examine if there is 

 not also an increase in the vital powers of the muscles and of the 

 motor nerves. There was no reason to reject the supposition that 

 the convulsing poisons were capable of increasing simultaneously 

 the vital powers of the nervous centres, of the nerves, and of the 

 muscles. Consequently, I was led to perform the following 

 experiments, which prove : 1st, that these poisons do not 

 increase the vital powers of the motor nerves and of muscles ; 

 2d, that they do not act as direct excitants upon these organs. 



On young cats, on birds, and on reptiles, I removed the whole 

 portion of the spinal cord which supplies nerves to the posterior 

 limbs. A few minutes after, I injected into the rectum a 

 solution of a salt of strychnine. Convulsions occurred only in 

 the anterior parts of the body, and when I excited either the 

 motor nerves or the muscles of the posterior limbs, contrac- 

 tions were produced exactly as in animals not poisoned, but 

 there was no appearance of convulsions. 



When the poison was placed directly on muscles or on 

 nerves, or when it was injected with blood in a limb separated 

 from the body, there was no appearance either of an exci- 

 tation, or of an increase in the excitability of the muscles, or of 

 the mDtor nerves. 



The experiments of Magendie, of Emmert,* and of Backer,f 

 have demonstrated that after a transverse section of the spinal 

 cord, between its two enlargements, convulsions may be produced 

 in the palsied limbs, when the animal is poisoned with strychnine. 

 All the physiologists who have performed this experiment have 

 found it perfectly exact. Nevertheless, J. W. Arnold, J maintains 

 that the action is much less considerable in the posterior limbs, 

 in that case, than when the spinal cord is uninjured and united 

 with the medulla oblongata, and he concludes that the poison 



* Exper. de effectu venenorum veget. americ. in corpus animale, 1817. 

 "I" Commentatio ad questionem physio)., ab Acad. Rheno traject, anno 

 1828, propositam. 



J Die lehre von der Reflex-function. Chap. ix. and x. 1842. 



