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fluid, in vapour, forty-six times for short operations on the human subject, and in the average of cases have produced the required insensibility within fifty seconds. In one instance insensibility was produced, a firm tooth was extracted, and perfect recovery occurred in forty seconds. As yet there has neither been vomiting nor other untoward symptom during the administration.

There is, however, a peculiarity in the action of this vapour to which I ought carefully to refer, viz. that insensibility from it intensifies after the inhalation of it is withdrawn. Thus in administering, whenever there is the least indication of its effects, such as winking of the eyelids or drop of the hand, the sign is given to stop the administration. The operator may now wait a few seconds and then proceed. The inhaler I have constructed for the administration of this new anæsthetic is before the Meeting. It is a simple hollow cone made of leather, and is furnished with two light silken valves for entrance of air and exit of vapour and breath. It is lined with domette set on a light frame or ring of metal. When the inhaler is not in use it forms a case for holding safely, in a bottle, four fluid-ounces of the anaesthetic liquid. This quantity is sufficient for twenty operations, of from one and a half to three minutes' duration, two drachms being the amount necessary for an operation not exceeding three minutes' duration.

The vapour described above will become, I believe, should experience confirm its safety, of general application as an anaesthetic for short operations; for long operations it will probably not replace the heavier anæsthetics. I am indebted to Mr. Ernest Chapman for the suggestion of the abbreviated name hydramyle.


In the course of the researches detailed in the preceding pages I have again, as in previous researches, been led to notice certain simple facts which lie in the path of inquiry, and which, though not necessarily belonging to it, are too prominent to be passed by without notice. I shall therefore offer a few notes bearing on three topics; and this the more readily, because it is rarely the case that so many eminent physiologists as are now present, each one interested in the subjects to be named, meet together to take part in discussion.


I have taken occasion several times to observe the effect of narcotic vapours on the minute circulation of the blood. I prefer to use the term "minute circulation" because it embraces the minute arterial and venous, as well as the capillary circulation.

In these researches the web of the foot of the frog was selected for observation, and I think on the whole with advantage. The following particulars were carried out in every case :—

(a) A large healthy frog was chosen, and one in which the web was very clear. (b) The same microscopic power, and that low-the inch or half-inch object-glass and A eye-piece (Ross)-was always employed. (c) The temperature of the air was kept the same during periods of observation, and the work was conducted during the same hours each day, viz. between the hours of 2 and 5 P.M. (d) The observations were never hurried; they occupied an average of three hours each, and every change of scene in the vessels through the various stages of narcotism and of recovery were carefully and systema

tically noted. (e) The animals were placed for narcotism in the small glass chamber now before the Members. The chamber as it is was finally constructed, after many essays, by my friend Dr. Sedgwick, and it answered admirably. The animal was placed, without any restraint, in the chamber; one foot was then gently drawn out on to the stage attached to the chamber, and the web was extended over the small glass plate. The animal being thus prepared, the web was brought under the microscope and the circulation examined. (f) The part of the circulation to be observed was so selected as to include a good view of an artery, a vein, and the smaller intermediate capillary vessels. (g) When the natural condition of the circulation was well observed the chamber was closed by the sliding cover, and through it the narcotic vapour, the effect of which upon the circulation was to be investigated, was gently passed. The vapour was driven over with hand-bellows from a small Junker's apparatus, manufactured by Messrs. Krohne and Sesemann*. By counting the strokes of the bellows it was possible to maintain the same current of vapour at all times. (h) And lastly, the web was sustained in the same condition of moisture, so as to prevent errors of observation due to evaporation from the tissues.

Such were the precautions taken; and I am inclined to think they were sufficient, although it will be a great satisfaction to me and an aid in my future labours to hear of any amendments or additions that may be suggested. The narcotic vapours used in the research were hydramyle, chloroform, bichloride of methylene, and absolute ether. In some particulars these acted precisely in a similar way, in other particulars they acted in a way more or less peculiar to themselves.

The first fact I would notice as common to the action of all the vapours used is, that no obvious change in the physical characters of the blood-corpuscles, red or white, was ever observable; neither was there any noticeable difference in the relationships of the red and white corpuscles to each other. The red corpuscles held their ways so long as there was motion in the centre of the blood-streams, while the white ones rolled along by the sides of vessels in the same manner as they did before the narcotism.

Another fact common to the action of all the vapours used was, that the first sign of arrested movement of the circulation commenced in every case on the venous side of the circulation, and consisted of a sort of pulsation or to-and-fro movement of the current through the vein; soon upon this the venous current became obviously slower and the vein dilated, while the arterial current remained, often for a long time, unchanged.

In every case the minute circulation remained long in force after the respiration had entirely ceased, and after all evidence of the continuance of life had entirely ceased. On the average the animals ceased to breathe for one hour and thirty minutes after the deep narcotism had set in; yet all the while the minute circulation was still playing with more or less of efficiency, and so long as it continued the chances of recovery were nearly certain. The cessation of the minute circulation was, on the other hand, the sign and proof of irrevocable death.

There was still another effect common to all the narcotics used. The circulation through the capillaries often stopped altogether, and for considerable intervals of time, when the reduction of the circulatory power was greatest. Under this condition the circulation, such as it was, was maintained by the arteries, in which the blood moved to and fro with occasional slow steady * Dr. Richardson here fitted up the apparatus, including small chamber, hand-bellows, and Junker's bottle, and showed the method by which it was worked.

onward movements. In the veins, too, there were now and then short movements, first as of impulse towards the heart, and then of retreat backwards; these movements in the veins were succeeded invariably by an increased and more perfect action of the arteries. During this state the capillaries may be said to have become almost indistinct, that is to say, no movement of corpuscles through them, into the veins, indicated their course; as channels they were left empty and transparent, and the return of the corpuscular current through them was at all times proof of the speedy return of the activity of life.

The changes named above were common to the action of all the narcotics named; but there were some striking changes peculiar to the substances themselves to which I must refer. The peculiarities were traccable, as it seems to me, to the weight, the solubility, and the chemical composition of the substance that was employed to produce the narcotic state.

When the substance was very light, of low boiling-point, and insoluble, the effect of arrest of the circulation was most rapidly developed, and at the same time was most rapidly removed. Thus hydramyle, the lightest, the first to boil on elevation of temperature, and the most insoluble, produced the quickest arrest of the venous current; but from its influence the animal was equally quick to recover, the general signs of recovery being secondary to the local return of the circulation.

When the substance was light and of low boiling-point, but comparatively soluble in blood, the time required to produce the slowing of the venous circulation was prolonged after the insensibility of the animal was complete; after even respiration had stopped, the extreme changes in the circulation were slowly developed; and although the insensibility might be deep and continuous, like to death itself, the actual temporary arrest of the arterial current was imperfectly pronounced. Absolute ether, which has a very low specific weight (720) and a very low boiling-point (94° F.), but which is soluble in blood to the extent of not less than eleven parts in the hundred, produced perfectly all the effects immediately named above. When the substance inhaled was comparatively heavier, of a higher boiling-point, insoluble, and contained as one of its elements an irritant, there was introduced a new phase, that is to say, the arterial vessels, as the animal came under the influence of the narcotic, were reduced in calibre. The changes of the circulation in this case were first marked in the retardation of the blood through the veins, then the vein increased in diameter, and there were signs of regurgitation of its blood; these indications were followed by what may be called irregular movements in the capillaries, and by reduction of calibre of the arteries. It was observed, nevertheless, that the narrowing of the arterial vessels, though well marked, was never so extreme as to prevent motion of blood in them; that is to say, the degree of arterial contraction was limited. I consider this to be due to the circumstance that the animal had always ceased to breathe, and the further absorption of the narcotic vapour had consequently also ceased, by the time that the action of the vapour upon the arterial vessels was developed.

During the period when the size of the arterial vessel was reduced, the motion of the blood in the capillary vessels fed by the arterial supply was modified; the blood flowing through the capillary channels moved less steadily, and was forced, if I may so express the fact, in pushes, as if there were intervals of relaxation of the arterial vessels during which the resistance to the impelling power of the heart slightly and slowly yielded. After a time the circulation of the blood through the artery became slower, 1871.


the capillaries were left empty, the venous current ceased, and the condition of temporary suspension of all circulation, except slowly, in the arterial supervened. The effects here named were well marked from the action of the chlorides; they were seen under the influence of bichloride of methylene, they were still more definite under chloroform.

To sum up, if my observations be correct, the action on the systemic circulation of the narcotic vapours named was seen to be primarily on the venous current or, I should more correctly say, was primarily manifested in the retardation of the venous current, secondly in the capillary, and finally in the arterial current. During recovery, moreover, the return of a steady onward current was manifested in the veins before it was restored in the capillary channels. This order of events coincides purely with the order of phenomena of death under the influence of narcotic vapours, as observed both in man and the lower animals. It is, I think, the invariable fact that the right side of the heart in such fatal cases is the first to cease its action, and in animals, when the heart is exposed to the air soon after the death, the right side is the first to recommence action. From these facts the inference, I think, is clear that the arrest of the circulation begins, during the narcotism, in the retardation of the venous current, secondly in the capillary, and lastly in the arterial current.

The course of recovery, when recovery takes place, appears to be preceded by some act of relief to the venous column of blood. The motion that remains in the arteries is not the first to increase, the circulation through the capillary is not first manifested; that which happens, as a distinct sign of recovery, is a movement onward by the veins; as this movement improves the movement through the arteries improves, the capillary vessels refill, and the circuit of the minute circulation is steadily and perfectly restored.

From these observations on the minute systemic circulation when the body is under the influence of a narcotic vapour of the irritant class, I infer that the changes of circulation observed do not proceed immediately from an action exerted by the narcotic vapour upon the extreme systemic vessels, but form an obstruction commencing on the venous side, and in the lesser or pulmonary circulation. When a warm-blooded animal is suddenly killed by a large dose of the vapour of chloroform, the lungs are invariably found blanched, the right side of the heart engorged with blood, and the left side empty of blood. We see in these conditions that of necessity, in the extreme parts of the systemic circulation of the animal, there has been retardation of the blood through the veins; and we may infer on the fairest, nay completest, evidence that the return of motion, which is seen commencing in the veins in the systemic circuit, is due to a returning current in the breathing-organs; in other words, the renewal of the active life of the animal recommences in passive breathing. The same order of phenomena happens, precisely, during the recovery of a warm-blooded animal, after apparent death from chloroform, under the influence of artificial respiration; for so soon as the animal recommences to breathe, however faintly, its return to life is secured.

The position then assumed, that the primary arrest of the column of blood during fatal narcotism is in the lesser circulation, we have to ask whether the arrest commences in the heart or in the lungs. The commonly accepted view has been that it commences in failure of the right side of the heart; but I incline to think that this view is incorrect, and that the positive source of failure is in the peripheral circulation of the lung. The vapour inhaled impresses, I think, immediately the minute circulation, and acts not by absorption into the blood, but by simple and instant contact with the minute

pulmonary vessels, so that there is immediate resistance to the passage of blood through them. Three well-observed facts support this opinion:-1st, the fact already dwelt upon, that in cases of rapid death the lungs are emptied of blood; 2nd, that the arrest of the systemic circulation commences on the venous side of the circulation, and is attended with filling of the veins; 3rd, that immediately after the death of the animal, if the chest be opened and the heart exposed, the right side of the heart, relieved of pressure, will immediately recommence to contract vigorously, showing that it is not itself paralyzed, but is restrained from action by mechanical resistance to its column of blood.

If the theory of the action of narcotic vapours thus propounded be correct, we ought to draw from it this practical lesson, that in introducing new narcotic vapours into practice, the utmost care should be taken to select those only that are negative in respect to their action upon the vessels of the minute circulation. A gas or vapour that asphyxiates but does not irritate may be safer than a gas or vapour that does not asphyxiate and does irritate; for the former, when it kills, kills by a secondary process that is preceded by a series of symptoms foretelling the danger; while the latter, when it kills, kills often by instantly shutting off the column of blood that is making its way to the air, and by so oppressing the heart that every attempt at action, under the condition produced, increases the injury.


I have endeavoured to show in the last section that under narcotism from certain narcotic vapours, the vapours of the chlorine series specially, there are two orders of cessation of the circulation,-the one primary, beginning in the lesser or pulmonary, the other secondary, beginning in the larger or systemic circulation. Coincidently with these changes I have, I think, observed, when there has been time for the development of the phenomena, two distinct series of convulsive movements or paroxysms of convulsion. I have noticed the same fact in drowning, and also in fatal sudden hæmorrhage, as in the process of killing animals, such as sheep. The phenomena may at any time be observed at the abattoir; they are in fact perhaps best seen in cases of rapid fatal hæmorrhage; and I am led to the conclusion that they have one common interpretation as to cause, the hæmorrhagic convulsions being the purest type of all. The convulsive actions, primary and secondary, are due, as it seems to me, to disturbance of the balance of supply of blood to the nervous and muscular centres. As a mechanism, the mass of nervous matter is the centre of reserved force, while the mass of muscle is the moving centre, the two centres being connected by an intervening nervous cord, and each supplied with the same blood. The two centres are held in counterpoise, as it were, by the blood. If there be, then, any disturbance of support in either centre, it will be indicated in change of function in the moving centre, in change of motion.

When we draw blood from the systemic circuit, or when through the lesser circulation we arrest the free current of blood through the systemic circuit, we destroy the balance previously existing between the muscular and nervous centres. If we could so exhaust the body that both centres should be exhausted together evenly, it is possible that there would be no change of motion in the moving centre; and, indeed, in some cases of disease we see the gradual and equal exhaustion without manifestation of the convulsive phenomena. But in cases of extreme and sudden break of balance, it follows necessarily that the balance shall be broken unevenly. It is in the muscular system

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