If it can be shown that the organs concerned in these functions receive several nerves limn the spinal cord, then we do not stand in need of vivisections to indicme to us that tl.e 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 flora 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 perforrned 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 I 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 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, and 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. A.nd 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 im 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 tbe 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 urine from the bladder by the catheter ; this he found to be acid, a sufficient proof that the urine was not alkaline when secreted, but un derwent the change during its stay in the bladder.