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1st. That, at first, the muscular irritability was greater in the 

 limb which had been deprived of the action of the spinal cord and 

 of the brain, than in the limb, deprived only of the action of the 

 brain. 



2d. That, at a variable time after the operation, the irritability 

 was at the same degree in the two limbs. 



3d. That, at last, the irritability became greater in the limb only 

 deprived of the action of the brain, than in the other.* 



The differences in the degree of irritability have been 

 observed : 1st. By the degree of the contraction under the influence 

 of the same excitation; 2d. By the duration of irritability. 



I have found that during a time, varying much according to sea- 

 sons, and to many other circumstances, the muscular irritability 

 increases in the two posterior limbs in a frog operated upon as I 

 have described, and that the increase was more considerable in the 

 limb where the nerves were divided than in the other. 



If we compare two frogs, one operated on as before, and another 

 having only had a division of all the nerves on one of the pos- 

 terior limbs, we find, a few days after the operation, that in the 

 four limbs separated from the body there are great differences as 

 to the degree and the duration of muscular irritability : 1st. The 

 three paralized limbs have a greater irritability than the one not 

 at all paralyzed. From the three paralyzed limbs the two in 

 which the nerves have been divided have both the same degree 

 of irritability, and more than the limb in which there was only 

 what Marshall Hall calls a cerebral paralysis. 2d. The irrita- 

 bility has lasted longer in the two limbs in which the nerves had 

 been cut, than in the two other limbs.; and from these two, that 

 in which there was a cerebral paralysis has remained longer 

 irritable. 



If we examine the irritability in the posterior limbs of two 

 frogs, operated on as aforesaid, for ten, twelve, or fifteen days, 

 then we find that it is nearly at the same degree in the three 

 paralyzed limbs, and greater there than in the non-paralyzed 

 limb. 



* There is, in these experiments, a cause of error, arising from the 

 existence on one side, and the absence, or, at least, a diminution in the 

 other, of the vital power of the motor nerves ; but the difference is trifling 

 when the nerves are divided very near their entrance in the muscles. 



