ganglia and their nervous filaments, as a distinct system, side by side with the cerebro-spinal system, we should probably discern a system as extensive as the cerebro-spinal itself, the centres of which, subject to certain voluntary control, condense and regulate the force which is expended on instinctive and involuntary action.

In simple truth, every human possesses two nervous natures. The one primitive, impulsive, instinctive, propelling, sustaining, and probably capable of no immediate or direct education; a nature seated in the ganglionic centres. The other secondary, receptive, directing, controlling, and susceptible of direct education; a nature seated in the cerebro-spinal centres.

We are all conscious of these two natures. We laugh, or cry, or move, instinctively, at something that affects or influences our organic system, and we control ourselves by an act of reason, or in other words an act of brain, and we say the thing was worth laughing at, or crying at, or moving for, or it was not worth it, as we say of a commodity we have bought, it was, or it was not worth what we gave for it. Thus, like the centrifugal and centripetal forces, the two forces in our body act, the one in subjection to the other; and if in any given case the emotional centres were to be excited to such degree that the controlling or cerebro-spinal organs lost their power, I see no reason why a person should not laugh, or cry, or move, under emotional impulse, until he died. In hysteria we see the effect of emotional impulse carried a long way towards death; in the dancing mania of the middle ages it was carried, in hundreds of cases, to the actual catastrophe of death.

And what is more, we are not only conscious of the two natures, but we refer the emotional nature to its true seat. We say of sorrow, "it sits heavy on the heart," and the glow of pleasure, or the gust of fear, are each immediately conveyed to us by sensations distinctly referable to the organic nervous centres, not to the reasoning brain, which at once endeavours

to exert its controlling, its balancing power. And so intermittent action of the heart, as it is due to what may be considered accidental failure contracted during an intense emotional effort, or to senile failure of organic function, is traceable, I think, fairly and logically to failure of those centres of the sympathetic system which supplement the true cardiac centres in supplying contractile power.

Of the nature of the failure of the nervous centres we know as yet so little, that the best pathologist can scarcely speak with authority. Indeed, the whole subject of the morbid changes belonging to the ganglia of the sympathetic system is still imperfectly known. But from a physiological point of view, we may safely infer that each centre of the nervous system is a reservoir or receptacle of force derived, not merely from the blood with which it is fed, but also from the parts which the nerves are said, incorrectly, to supply. In these centres, molecular changes, as yet, to us, imperceptible, may be understood as inducing deficiency of retaining power, and what is commonly called nervous debility and exhaustion, so that the centres cannot persistently carry on their allotted natural function.

It will add to the truth of the theory I have put forward respecting the seat of disease in cases of intermittent pulse, to refer to an experimental truth adduced in my original paper. At the time when that paper was written and my mind was charged with the idea of the cerebral origin of intermittent action, I conceived it would be possible to induce intermittency by temporarily destroying cerebral function. I therefore entirely destroyed brain function by freezing the hemispheres in an inferior animal, but, although by this method the most complete insensibility was induced, there was no satisfactory indication, as I then reported, of intermittent motion of the heart. I thought this result was due to the circumstance that the parts at the base of the brain had not been affected. But

I have since found that if an animal be rendered insensible by exposure of the whole cerebrum to extreme cold, there is no intermittent action: if, however in this state the animal be allowed to inhale vapour of chloroform, the intermittent action is at once set up, the ganglionic organic centres being now involved. At the same time, the ganglionic system may be influenced by some physical injuries of the cerebral surface, without implication of the voluntary nervous system: this is occasionally seen in cases of concussion.

The recent researches of Waller, Rutherford, Wood of Philadelphia, and others, on the functions of the pneumogastric, deserve, finally, a word. It has been so clearly demonstrated that irritation of the pneumogastric produces what is called 66 slowing" of the action of the heart, the inference seems to come naturally that intermittent action is or may be a result of such irritation. But direct observation does not support this view. When the pneumogastric in the neck is subjected to irritation, the action of the heart is lowered, and there are induced signs of faintness, and what Waller calls asthenia. Waller has in fact induced temporary faintness in the human subject by mechanical irritation of the pneumogastric, for the purpose of aiding in the reduction of dislocation.* But from what I learn from observation on the inferior animals, the same irritation, while it produces symptoms of faintness and asthenia, does not produce the intermittent cardiac action which is now under our consideration; and, what is equally to the point, patients suffering from intermittent pulse are not necessarily subject to symptoms directly indicating irritation of the pneumogastric.

I repeat, therefore, my present conviction, as I close this section of the subject, that the seat of the nervous lesion is in the nervous centres which supply the reserve contractile power of the heart, I mean the sympathetic nervous centres that go to *Proceedings of the Royal Society, May, 1870.

feed the heart, and that the change in those centres, whatever it may be physically, leads to their failure as reservoirs or condensors of force.*

* I must not allow this paper to leave my hand without acknowledging a work indifferently known, and yet full of the most suggestive and original thought. I refer to the work of Dr. Davey, of Northwoods, Bristol, on "The Ganglionic Nervous System." Dr. Davey has most clearly appreciated the functions of the organic nervous centres, and has described his views in a volume which, when the jealousies, prejudices, and ignorances, that always beset the present, concerning the present, have passed away. will be discovered by some future and unbiassed scholar as a neglected classical work of the physic of the nineteenth century.

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CHAPTER V.

ON THE SIGNIFICANCY AND PERSISTENCY OF INTERMITTENT

PULSE.

The Significancy of Intermittent Pulse.

In itself, when it is not present in an exaggerated degree, intermittency of the pulse is less dangerous than it seems. It does not, as might be feared, carry with it the necessary idea. of sudden dissolution from heart disease, for, as I have elsewhere shown, the heart is the regulator, not the prime mover, of the circulation. The harmlessness of the symptom in its moderate development is best shown by the facts of its common occurrence after middle age, and the long duration of life in many of those who present it.

At the same time the symptom has its significance. Occurring in infancy, it is an important indication of the existence of serious nervous derangement. Occurring in adults it has the same meaning, and tells the story of commencing failure of power. Occurring suddenly after any great event, which has told upon the mind, it may be a sign of serious import. My own experience connects it as the first physical indication of derangement in three cases of disorder of mind in which suicide was attempted, in two of the cases successfully. Further, it becomes an embarrassing sign in all conditions where there is diminished condensation of force in the nervous centres, where force is either not laid up or is given out too freely.

In persons advanced in life, and in persons prematurely old, intermittency is often the herald of symptoms of nervous failure. In these examples the patient has sometimes a sin

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