PHYSIOLOGY OF THE NERVOUS SYSTEM. 



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\vhat exalted. The slightest touch upon the 

 surface of the body, even a breatli of wind 

 blown upon it, will cause a general or partial 

 convulsive movement. The whole extent of 

 the spinal cord is in a state of excitement, and 

 even the medulla oblongata may be involved 

 in it, whence the closed jaws, the spasmodic 

 state of the facial muscles, the difficult degluti- 

 tion. When this polar excitement is raised to 

 its highest degree, the slightest mechanical sti- 

 mulus applied to any one point of the cord 

 affects the whole organ and throws all the mus- 

 cles which it supplies into spasmodic contrac- 

 tion, just as the least stimulus to peripheral 

 parts has the same effect. 



It is a very interesting fact, which I have fre- 

 quently satisfied myself of by careful examina- 

 tion, that, however great the polar excitement 

 may have been into which the cord has been 

 thrown by strychnine, it exhibits no change of 

 structure which can be detected by our means 

 of observation. The nerve tubes and other 

 elements entering into the formation of the 

 cord have preserved their natural appearance 

 in all the cases which I have examined. 



Opium has the effect of creating a similar 

 state of polarity in the cord. This is most con- 

 spicuous in cold-blooded animals ; it produces 

 a similar effect in the warm-blooded classes, 

 but in a much less degree. Hence there is 

 an objection to the use of opium in large doses 

 in cases of tetanus; and experience has shewn 

 the inefficacy and the injurious influence of this 

 drug when administered in large quantities. 

 When the cord is in this state of excitement, a 

 stimulus applied to one part may excite a re- 

 mote part of it with great facility. 



The curious tendency already referred to, 

 which the male frog has to grasp objects pre- 

 sented to them by his anterior extremities, is to 

 be attributed in part to a spontaneous exaltation 

 of the polar force of the cord which takes place 

 at the copulating season, in the spring of the 

 year, and which is associated with an extraor- 

 dinary developement of the papillary texture of 

 the integument of the thumb. 



This exaltation of the polar force of the cord, 

 in connection with the generative function, is a 

 point highly worthy of the attention of the 

 physiologist as offering some explanation of the 

 sympathy which exists between different organs, 

 between those even which are remote from 

 each other, during the rutting season, or during 

 utero-gestation. 



It is worthy of notice here that cold has a 

 considerable influence in controlling this polar 

 state of the spinal cord, and of other nervous 

 centres likewise. Ice applied along the spine, 

 or the cold douche, may be frequently em- 

 ployed with great benefit in cases of muscular 

 disturbance dependent on this polar state of the 

 cord. It seems to me more than doubtful that 

 many of those drugs which have the character 

 of possessing a sedative influence upon the 

 nervous system can be employed for mis pur- 

 pose either with safety or advantage. This 

 applies certainly to hydrocyanic acid and to 

 opium in large doses ; animals poisoned by 

 these substances become convulsed before 



death, and this denotes their tendency to exalt 

 the polarity of the cord. Coniuin and bella- 

 donna, according to my experience, exercise the 

 most beneficial influence of any of the sedative 

 drugs, and I have found them very useful in 

 restraining the cramps and starlings in para- 

 plegic cases. 



I have ascertained by several experiments 

 that the inhalation of ether has considerable 

 effect in controlling the natural polar state 

 of the cord, as well as that which may be 

 produced by strychnine. A pigeon deprived of 

 its cerebral hemispheres lives in a state of sleep 

 for a considerable time ; it flies when thrown 

 in the air, spreading and flapping its wings ; 

 stands when placed on its feet. A bird thus 

 mutilated was made to inhale ether ; it could 

 not stand, and when thrown into the air it fell 

 to the ground like a heavy log, its wings 

 remaining applied to the sides of its body, or 

 if the wings were drawn out as it was thrown 

 into the air, they quickly collapsed. As soon 

 as the effects of the ether had passed off, it 

 stood and flew as before. I gave strychnine to 

 a rabbit, a guinea-pig, and a dog, so as to 

 excite the tetanoid state. Immediately the 

 spasms showed themselves, I brought it un- 

 der the influence of ether; the spasms ceased 

 immediately, and the animal became perfectly 

 relaxed ; but as soon as the effects of the ether 

 passed off, the spasms came on again, but were 

 soon -subdued by a fresh inhalation of ether. 

 And thus I found that the life of an animal 

 poisoned by strychnine could be greatly pro- 

 longed through successive inhalations of ether; 

 for animals of the same kind, poisoned by 

 equal doses of strychnine, but not subjected 

 to the influence of ether, perished very rapidly. 



The examples which show that the spinal 

 cord possesses the power of reflecting sensitive 

 impressions are chiefly derived from disease. 

 Every practitioner is familiar with the pain in 

 the knee which accompanies the early stages of 

 disease of the hip joint. The patient some- 

 times refers his sufferings so exclusively to the 

 former joint, that the disease of the latter may 

 be entirely overlooked by his medical atten- 

 dant. Yet the really painful part is healthy, 

 while the hip joint is the seat of a morbid 

 process. The pains which are felt in the thighs 

 from the presence of a stone in the bladder, 

 and the itching which is referred to the extre- 

 mity of the prepuce from the same cause, are 

 phenomena of the same nature. Pain in the 

 right shoulder from irritation of the liver is a 

 well-known sympathetic sensation : sometimes 

 this pain extends over a very large surface. 



Numerous other instances of similar sympa- 

 thetic phenomena might be adduced, but the 

 above are sufficient for our present purpose. 

 Taking into account the well-proved fact that 

 nerves form no real junction of their fibres 

 in their anastomoses, and that there is no more 

 than a simple juxta-position of the nerve-tubes 

 in these anastomoses, it is plain that we must 

 trace these fibres up to the nervous centres to 

 discover any connection between the fibre first 

 irritated and that to which pain is referred. In 

 the case of hip-joint disease, the nerves of the 



