60 



acts much more on the medulla oblongata than on the spinal 

 cord. 



Sometimes, as Arnold says, it occurs that the action of strych- 

 nine, in mammalia and in amphibia, is not so powerful in the 

 palsied parts, after the section of the spinal cord, as in the 

 non-palsied limbs. As to mammalia, the reason of this difference 

 is the diminution in the quantity of blood received by the part 

 of the spinal marrow separated from the encephalon. As to 

 amphibia, it is easily seen that immediately after the section of 

 their spinal cord, the reflex faculty in the part separated from 

 the encephalon is very weak, and if, then, strychnine is given to 

 the animal, it does not act very strongly ; but if the poison is 

 given two or three hours after the section of the spinal cord, 

 then the reflex faculty is very powerful and the poison acts vio- 

 lently, and sometimes more than if the spinal cord was uninjured. 

 In birds, which, as I have discovered, have constantly a power- 

 ful reflex faculty after the section of the spinal cord, strychnine 

 acts very energetically. 



Lately, Stannius and Cl. Bernard have supposed that strych- 

 nine, instead of acting on the spinal marrow, acted on the nerves 

 of sensibility, and more particularly on their termination in the 

 skin. They base this hypothesis on some experiments, of which 

 only one is important. After the section of the spinal cord, at 

 the brachial enlargement, upon a frog, the animal is poisoned 

 with strychnine, and then convulsions occur nearly at each vo- 

 luntary or respiratory movement. But if the sensitive roots of 

 the spinal nerves are cut, the convulsions cease immediately. 



Now, it is evident that this fact does not prove what Stannius 

 and Bernard have supposed ; because it may be explained as 

 well by admitting that convulsions are produced only in conse- 

 quence of an increase of the reflex faculty of the spinal cord, 

 as by the hypothesis of Stannius. 



Van Deen * relates an experiment which is in opposition to 

 the theory of Stannius. If we take a frog prepared exactly as 

 in the experiment of this physiologist, we see that tetanus oc- 

 curs when the animal is thrown on the floor. In this case 

 tetanus is produced, although the sensitive roots are cut and 

 unable to act ; therefore tetanus is a consequence of an increased 



* Loco cit. p. 123. 



