98 



M. Monod* has related the case of a man who, after having 

 felt a sudden pain in his back, became paralyzed in the motion 

 of the right inferior limb. Sensibility was entire on this side, 

 but on the left side, where the movements were entire, sensibility 

 was entirely lost from the breast to the foot. There was at first 

 no fever. The patient died 34 days after the beginning of this 

 affection. 



The brain and its membranes were normal. A hemorrhage 

 had taken place, and blood was found in the right side of the 

 central gray matter, in the neighborhood of the anterior column 

 in the dorsal and lumbar regions. 



This case is assuredly a very remarkable one, and in accord- 

 ance with my experiments. 



The conclusion to be drawn from these four cases is, that in 

 man as well as in animals, there appears to be a crossing of the 

 sensitive nerve-fibres in the spinal cord. 



XXX. ON THE DIFFERENT DEGREES OF EXCITABILITY OF THE 

 DIFFERENT PARTS OF THE SENSITIVE NERVE-FIBRES. 



It is a well-known fact, that an excitation of the skin or of a 

 mucous membrane, produces a greater pain or a greater reflex 

 action than that of the nerve trunk, from which these parts re- 

 ceive their nerve-fibres. For instance, a slight excitation of the 

 laryngeal mucous membrane produces coughing, while an excita- 

 tion of the vagus nerve very rarely produces the same effect. 

 Therefore, there is a notable difference between the peripheric 

 extremity of a nerve-tube and its part contained in a nerve- 

 trunk. 



The existence of a peculiar organ in the skin (the corpuscles 

 of touch of Wagner) has not much (if it has anything) to do with 

 the different degrees of excitability of nerve-tubes in the skin 

 and in the trunks of nerves. The corpuscles of touch do not 

 exist in the mucous membranes, and if they exist in the skin of 

 frogs, turtles, etc., it is in a very small number ; and, neverthe- 

 less, the degree of excitability of nerve-fibres in these parts is 

 much superior to that of the fibres of the nerve-trunks. 



Some very striking differences exist in the degree of excita- 



* Bulletin de la Societe Anatornique, No. xviii. p. 349. 



