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Avhicli is fixed by its other extremity, we find that every time the muscle tends to 

 contract, there is an excitation of the nerve lying upon it, and a contraction of the 

 muscle to which this nerve is distributed. Hence it is not necessary for muscle to 

 contract in order to produce in nerves in contact with it a galvanic excitation. I 

 repeat that it is sufficient that they tend to contract. Now I have found that the 

 greater is the resistance to the contraction of the muscle the greater is the galvanic 

 excitation that it gives to nerves in contact with its tissue. On the contrary, if there 

 is no resistance at all, as already shewn by Prof. Matteucci, after the. section of the 

 tendon, then the galvanic excitation of the nerves in contact with the contracting 

 muscle no longer exists." 



In this manner Dr. Brown- Sequard attempts to explain, with what, 

 as we have already said, appears to us singular ingenuity, the pain 

 accompanying contracted muscles, cramps, spasms, contraction of the 

 uterus, &c. &c. 



What is to be considered as the true cause of the increase of sen- 

 sibility which follows a division of a lateral half of the spinal marrow, 

 and is observed to take place on the same side as the lesion ? Hy- 

 peresthesia (or at least such augmentation of sensibility as we can 

 discover in animals by pricking, pinching, &c.) seems to result from 

 two distinct conditions, viz. increased vascularity of the surface, and 

 also increased vascularity of portions of the cerebro- spinal centres. 

 Of the first we have a familiar example, in the great sensitiveness of 

 a portion of the skin irritated by the application of a sinapism ; the 

 peripheral expansions of the nerves seem to become, in consequence 

 of the greater supply of blood, more acutely sensitive to impressions 

 made upon them, to undergo, in fact, an exaltation of function. Of 

 the second we have an illustration in the increased sensibility, which 

 forms so striking a symptom of the early stages of cerebro-spinal 

 meningitis ; in this case, the increased vascularity of the central 

 nervous system is accompanied by an increase of sensibility of the 

 surface. We know that when the sympathetic nerve is divided in 

 the neck of a rabbit, the ear, on the same side, becomes warmer, more 

 vascular, and more sensitive than the other, and that the same conse- 

 quences are met with, on the same side as the section, in the posterior 

 limb, after division of a lateral half of the spinal cord. We are 

 therefore, at first, naturally led to suppose that in each experiment 

 the vaso-motor nerve fibres being divided, and the blood-vessels 

 paralysed, the increased vascularity consequent upon this gives rise 

 to the increase of sensibility. An exceedingly interesting experi- 

 ment of Dr. Brown- Sequard' s proves that in the latter instance, at 

 all events, there is another cause for the hyperesthesia to be sought 

 for. In his paper entitled " Experimental Researches on various 

 questions concerning Sensibility," read before the Royal Society in 

 May, 1860, he says that in a rabbit, all the parts of one of whose 

 hind limbs were amputated, except the nerves, and in which the 

 toes are, after a time, about losing their sensibility, in consequence of 

 all circulation of blood being at an end in the limb, there is never- 

 theless a rapid and very notable return of sensibility on dividing the 

 posterior columns of the spinal cord in the dorsal region. It is ob- 



