obliged him to lead rather a sedentary life; his usual state of health was good, his habits very regular, his diet ordinary and plain; he had used soda water, magnesia, and the alcalies, without any advantage; I proposed he should try a mild acid plan, and pointed out to him the requisite precautions that should be adopted to prevent the retention of a calculus in the bladder, but I have not been sofort unate as to learn any further particulars respecting this gentleman, who is resident in Ireland.

There are many circumstances connected with the history of kidney calculi, which I have not adverted to, either for want of practical information upon the subject, or because I shall have a preferable opportunity of recurring to them in the observations I have yet to make on calculi of the bladder.

ART. V. Some Observations relating to the Agency of Galvanism in the Animal Economy, in a Letter addressed to the Editor of the Quarterly Journal of the Royal Institution. By A. P. Wilson Philip, M.D., F.R.S.E. &c. Worcester, July 22d, 1819.

SIR,

As you were so good as to publish, in the last Number of the Quarterly Journal, my reply to a Paper in a former Number of that work, in which the accuracy of certain experiments, detailed in my Inquiry into the Laws of the Vital Functions, is called in question; I take the liberty of transmitting to you some observations on the subject of these experiments. If they appear to you to deserve a place in the above Journal, you will oblige me by inserting them.

While the writers who have done me the honour to notice my inquiry, have admitted the accuracy of the other inferences, those from the galvanic experiments have, by some, been called in question. I have carefully considered what has been brought against them, without being able to perceive its force. I cannot help ascribing it, in some degree, to the novelty of the subject, and to the circumstances which originally induced me to trouble you; from which it appears, that some who must be supposed

well versed in medical science, in the first instance objected to these inferences. I also, in some degree, ascribe it to the arguments relating to this part of the subject being necessarily dispersed through a great part of the treatise, even in the last edition, in which I have endeavoured, as far as was consistent with the general arrangement, to bring them into one view. This prevents their being fairly considered, except at the expense of much trouble. The object of the present pages is to communicate to the reader what I have attempted to ascertain respecting the agency of galvanism in the animal economy, in a concise and more connected form, and consequently one which affords less room for misconception.

Some, who will not admit that any argument in favour of the identity of the nervous influence and galvanism can be derived from the experiments in question, allow, that they prove the latter to be capable of acting as a substitute for the former. This language, I confess, I do not understand. Whatever is capable of acting as a substitute for the nervous influence, must possess its properties. I have said, that such and such are the properties of this influence, and that galvanism, possessing all these properties, we have reason to regard the two powers as identical. To refute this inference, it must be shewn, that I have mistaken the properties of the nervous influence, or that galvanism does not possess these properties, or possesses others inconsistent with those of the nervous influence. Although all will grant the truth of this position, yet in no instance do those, who, admitting the accuracy of the experiments, controvert my inference from them, attempt to prove that in any of these respects I have been misled. They satisfy themselves with assertions, that my conclusions in this part of the subject are less correct than in others, that it is still involved in obscurity, &c. Without regarding general assertions of this kind, which, it is evident, unless they are the legitimate result of a fair statement of facts, amount to nothing, let us endeavour to ascertain how far our present knowledge enables us to go towards determining the question before us.

I have endeavoured to shew that the functions of the nervous influence are those of conveying impressions to and from the

sensorium, of exciting the muscular fibre, of separating and recombining the elementary parts of the blood in the formation of the secreted fluids, and of causing an evolution of caloric from the blood.

That the nervous influence is the means of conveying impressions to, and from, the sensorium, will not be denied.

That it acts merely as a stimulus, without bestowing any power on the muscular fibre, appears from the thirty-second experiment of the above-mentioned Inquiry, which shews, that an artificial stimulus more quickly exhausts the excitability of this fibre, when it is exposed at the same time to the operation of the nervous influence, than when it is exposed to the effects of the artificial stimulus alone.

That the nervous influence is an agent in the formation of the secreted fluids, we learn from experiments which shew that when this influence is withdrawn from the lungs and stomach, these organs in all other respects remaining in the same state, their secretions are deranged. Fluids, indeed, are still deposited in their cavities, and apparently as copiously as before; but these fluids no longer undergo the proper change. Those of the lungs assume an appearance differing little from that of the sanious discharge from some kinds of wounds. The fluids of the stomach, we know, are no less altered, because they no longer make any impression on the food. These facts do not rest on the accuracy of my experiments alone, as many of my opponents seem to imagine. They were long ago pointed out, as stated in the above Inquiry, by the experiments of Haller, and other Physiologists of the first name. I only add my testimony to theirs in proof of them*. It appears, then, that the nervous influence is necessary to the function of secretion. It either bestows on the vessels the power of decomposing and recombining the elementary parts of the blood, or effects those changes by its direct operation on this fluid. From many facts stated or referred to in my In

* My Inquiry into the Laws of the Vital Functions, Exper. 44, 45. See also Exper. 54, 55, 56, 57, 58. The page and number of the experiment referred to in the following paper are those of the second edition of the Inquiry.

quiry it appears, that the vessels possess no powers but the muscular and elastic; and that the former, as well as the latter, is independent of the nervous system*; nor is it possible to conceive any modification of these powers, by which they could become chemical agents, and thus be enabled to separate and recombine the elementary parts of the blood. The first of the above positions may, therefore, be regarded as set aside; and the necessary inference seems to be, that in the function of secretion, the vessels only convey the fluids to be operated upon by the nervous influence.

That the evolution of caloric is effected by the state of the nervous influence, appears from many experiments. Mr. Brodie has shewn that in proportion as the action of the brain is debilitated, the evolution of caloric is lessened †; and it appears from experiments which I have laid before the public, that lessening the extent of the nervous system, by destroying portions of the spinal marrow, has the same effect. But it also appears from a great variety of facts, that its evolution depends equally on the state of the blood. It is needless to enumerate the various phenomena of the living animal which support this position, with which every Physiologist is familiar; but it may be proper to observe, that I have found by many experiments §, that if the circulation be supported by artificial respiration in the newly dead animal, an evolution of caloric continues to take place, which is not found to be the case when the circulation is allowed to cease. Thus we see that the evolution of caloric in the animal economy depends equally on the state of the nervous influence, and that of the blood, and, consequently, like the formation of the secreted fluids, arises from their joint operation. On this account I have said, "If caloric be admitted to be a substance, its evolution from the blood being effected by the same means by which the secreted fluids are formed, it must be regarded as a secretion;"

* Exper. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 31, 32, and the observations under Exper. 32.

+ Croonian Lecture for 1810, and Philosophical Transactions for 1812. The above Inquiry, Exper. 54, 55, 56.

The above Inquiry, Exper. 64, 65, 66, &c.

this view of the subject appearing best calculated to convey an idea of the manner in which its evolution takes place. I know of no definition of the term secretion, as applied to the matter secreted, but a tertium quid produced by the action on each other of the nervous influence and the blood.

Such is a cursory view of the proofs that the functions of the nervous influence are those above stated, namely, to convey impressions to and from the sensorium, to excite the muscular fibre, to separate and recombine the elementary parts of the blood in the formation of the secreted fluids, and to cause an evolution of caloric from the blood. We are now to inquire how far galvanism is capable of these functions.

That galvanism is capable of passing along the nerves both to and from the sensorium, and therefore of conveying impressions in either direction, will not be questioned.

It will also be admitted, that it is not only capable of acting as a stimulus to the muscular fibre, but that, with the exception of the nervous influence itself, we know of no other agent which possesses this property in so remarkable a degree.

With regard to the function of secretion, that galvanism is capable of decomposing and recombining the elementary parts of the blood in precisely the same way in which they are decomposed and recombined by the nervous influence, if applied to that fluid under the same circumstances, appears from experiments related in my Inquiry*, which were not performed in private, but in the presence of many competent witnesses; and not by me alone, but by others in my absence with the same results.

That galvanism is capable of causing an evolution of caloric from arterial blood, that is blood which has not already undergone the secreting process, appears also from experiments related in the same Inquiry +.

It is further shewn in that Inquiry, that in the human body itself, galvanism can be made to perform the functions of the nervous influence. In apoplexy, for example, where we see, from the failure of this influence, the function of the lungs im

* Exper. 70, 71, 72, 73.

+ Exper. 76, 77, 78, 79.