PHYSIOLOGY OF THE NERVOUS SYSTEM. 



721s 



functions with which they have to do are, to a 

 certain extent at least, influenced by this organ. 

 Now it is almost certain that the heart and 

 kidneys receive filaments from the cord which 

 pass to them chiefly in the sympathetic nerve ; 

 but as it is equally certain that they receive 

 nerves from other sources likewise, as from the 

 vagus nerve, and the proper filaments of the 

 sympathetic, it would be erroneous, so far as 

 anatomy teaches us, to affirm that these organs 

 were wholly dependent on the cord. 



As regards the heart, observation and expe- 

 riment on man and animals tend to confirm the 

 conclusion which anatomy indicates, namely, 

 that while the heart possesses a certain inherent 

 power, and while it has an immediate connec- 

 tion with the medulla oblongata and with the 

 sympathetic, it is also not independent of the 

 spinal cord. A slight injury to the cord or a 

 chronic lesion of it affect the heart but little or 

 not at all, because of its other sources of in- 

 nervation ; but a sudden and extensive injury 

 to the cord, or a rapidly-developed destructive 

 disease of it, materially depresses and weakens 

 the action of the heart, and thereby the general 

 circulation. The experiments of Clift, Wedeme- 

 yer, and Nasse may be cited as leading dis- 

 tinctly to this conclusion. Nasse's experiments 

 were on dogs, in which he maintained artifi- 

 cial respiration; he found that as soon as the 

 spinal cord was destroyed, the heart failed so 

 completely that the jet of blood from the femo- 

 ral artery, which before had gone to a distance 

 of some feet, could not reach as many inches, 

 or the blood did not escape per saltum from 

 the wounded artery. In performing a similar 

 experiment, Longet compared the action of the 

 heart in two dogs, destroying the cord in one, 

 but allowing it to remain intact in the other, 

 and he found that in the animal whose spinal 

 cord was destroyed the cardiac movements be- 

 came enfeebled in a very striking manner, 

 when compared with those of the animal 

 whose cord was left uninjured. 



If, then, we can prove that the spinal cord 

 exercises an influence upon the central organ 

 of the circulation, there can be no doubt that 

 its power extends to the peripheral parts of the 

 circulating system, to the capillary vessels, 

 and, therefore, that injury or disease of it, espe- 

 cially if sudden or extensive, must to a certain 

 extent affect the functions which are performed 

 through the agency of these vessels, namely, 

 nutrition, calorification, and secretion. 



It seems most probable that it is only in this 

 secondary manner that the influence of the 

 spinal cord becomes extended to these func- 

 tions, and that they suffer, when, through lesion 

 of the cord, this influence has been greatly 

 diminished or removed. The indications of 

 its connection with nutrition and calorification 

 are derived from the wasting and the coldness 

 which are manifest in the paralysed parts when 

 there is lesion of the spinal cord of a depress- 

 ing kind. Sometimes, too, the nutrition of 

 these parts is so feeble that gangrenous sloughs 

 are formed on parts exposed even to slight 

 pressure. This is more apt to be the case where 

 the disease of the cord has been of a destruc- 

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tive kind, and has involved a considerable 

 portion of the organ and of the roots of its 

 nerves. 



The influence of the spinal cord upon secre- 

 tion has been inferred chiefly from the frequent 

 occurrence of an alkaline state of urine in con- 

 nection with injuries of that organ, arid less 

 frequently in diseased states of it. The urine, 

 when passed, is found to be highly alkaline 

 from the existence in it of a large quantity of 

 carbonate of ammonia. The urine, in cases 

 of this kind, is very apt to contain more or 

 less of what has been very commonly, although 

 erroneously, called ropy mucus, which is in 

 truth pus formed from the mucous membrane 

 of the bladder. This membrane is irritated 

 and inflamed by the sojourn in it of the urine 

 which the paralysed bladder is unable to expel. 

 The secretion of a large quantity of phos- 

 phate of lime and of mucus, and afterwards of 

 pus, is provoked by inflammation of the vesical 

 mucous membrane. And the addition of these 

 matters to it, especially the former, neutralises 

 all free acid and gives rise to decomposition of 

 the urea, and the production thereby of car- 

 bonate of ammonia. The alkalescence of the 

 urine favours the precipitation of the triple 

 phosphate. Hence urine obtained from pa- 

 tients suffering under spinal disease resembles 

 very closely that of patients with diseased blad- 

 der without spinal disease. We may see in it 

 mucus or pus globules, triple phosphates, blood 

 particles, and amorphous masses of phosphate 

 of lime mingled with the mucus. But in 

 some instances the period of the sojourn of 

 the urine in the bladder appears too short for 

 these changes to take place ; and hence it has 

 been supposed that the urine may be secreted 

 alkaline by the kidneys. Mr. Smith, of St. 

 Mary's Cray, in Kent, made experiments on 

 this subject by washing out the bladder care- 

 fully with warm water several times, withdraw- 

 ing the water each time and testing for am- 

 monia until all indication of its presence 

 ceased. He then injected a small quantity of 

 clear water, and allowed it to remain fifteen or 

 twenty minutes; it was then drawn off, and the 

 odour of ammonia could be distinctly per- 

 ceived. It is to be regretted that a more accu- 

 rate test of the presence of ammonia had not 

 been used. Admitting, however, that am- 

 monia did exist in this fluid, the experiment 

 by no means disproves the formation of am- 

 monia in the bladder. So small a quantity 

 of urine as might trickle into the bladder in 

 twenty minutes might readily be neutralised 

 and decomposed by any alkali or mucus pre- 

 sent in the bladder which might have eluded 

 the previous washing out of that organ. If the 

 secretion of urine in the alkaline state were 

 common, it might reasonably be expected that 

 such urine would be more frequently met with 

 than it is in spinal complaints. Dr. Golding 

 Bird, indeed, states that in the case of a woman 

 in Guy's Hospital, labouring under complete 

 paraplegia, and passing, with the aid of a ca- 

 theter, fetid, alkaline, and phosphatic urine, he 

 washed out the bladder with warm water, and 

 after the lapse of half an hour obtained some 



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