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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 traceable, 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 reins, 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,
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 minuto
pulmonary vessels, so that there is immediate resistanco 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.
ON CONVULSIVE MOVEMENTS DURING NARCOTISM. 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 that the failure of blood is first felt. The nervous centres, protected from the eifects of sudden pressure by their envelopment of bony structure, feel the shock of the exhaustion secondarily. Thus the muscle suffering a reduced resistance of blood to the nervous stimulus, contracts as if it had received an excess of stimulus, and the phenomenon of primary convulsion is developed; in hæmorrhage this convulsion immediately precedes deliquiųm or syncope. In brief time, the nervous centres themselves becoming exhausted, the convulsions cease, and none but the muscular movements of the organic life, respiration and circulation, remain. These while they last feed still in a passive state the nervous centres and muscular centres ; and if the cause of exhaustion at this stage be stopped and the body be resupplied with means of life, recovery takes place without the necessary return of convulsive action ; but if the exhaustion proceed, then follows the secondary phase, the failure of the organic system, and with that a repetition of the phenomenon of primary failure, viz. a second general convulsion, terminating in death. The convulsion of hæmorrhage is, I repeat, the typical form of the condi
I tions I have portrayed ; but in death from chloroform and similar narcotics, the phenomena are sometimes equally striking. The convulsion and rigidity which mark the second degree of narcotism indicate the first break of balance between the nervous and the muscular centres; the period of the third and fourth degrees of narcotism, during which there is complete paralysis of voluntary and of conscious power, marks the interval when all life is suspended on the organic or vegetative nervous system; the final convulsion that precedes death marks and proclaims the moment when the organic force itself breaks down, leaving the whole organism motionless and, as we say, dead.
On CONDENSATION OF WATER ON TIE BRONCHIAL SURFACE DURING NARCOTISY.
It has occurred to me often to observe that the physiological action of narcotic vapours during inhalation is greatly modified by the condition of the atmospheric air in respect to its dryness and its moisture. When the atmosphere is extremely dry, the action of a narcotic vapour is greatly increased, and recovery from its effects is remarkably easy; on the contrary, when the air is saturated with water vapour the action is impeded; and if the air be at the same time cold and moist, the process of narcotism is often greatly impeded, while recovery after it has been established is prolonged in proportion. But the fact I wish particularly to bring forward is, that when the body of an animal becomes profoundly narcotized, and the insensibility is long maintained, during conditions in which the air is cold and moist, there occurs not unfrequently an actual condensation of water in the minute bronchial passages, which condensation leads to as low asphyxia, and, if it be continued, to actual death. This accident is best seen in cases of narcotic poisoning from hydrate of chloral ; it may also be observed after poisoning from opium and other narcotics, as well as after long exposure to extreme cold.
There are two causes at work to produce the condensation : the one is the obstacle to evaporation of watery matter from the surface of the animal membrane into the air; the other the deficiency of force, in an animal whose general temperature is reduced, to raise the vapour of water from the blood, and to expel it from the pulmonary organs in the state of vapour.
Whenever in any case condensation of water, from the causes named, is set up, the danger continues in an increasing ratio ; for the condensation tends to shut off the air from contact with the blood, the temperature of the
body (dependent always on the perfection of the respiratory process) decreases, and at last the respiratory change is prohibited altogether.
It is important in the extremest degree to remember the fact thus named in the treatment of cases of poisoning during which the animal heat is reduced. It will often turn the scale, in such instances, in favour of return to life, simply to place the body in a warm and dry air.
The fact is also of great interest, in a practical and physiological point of riew, in relation to the phenomena of some exhaustive diseases. The cold sweats that are seen on the surface of the body in syncope, in the later stages of phthisis pulmonalis, and on the approach of death in many diseases, as also the chest-rattles, are due to the cause I have named'above--condensation. They are evidences that the body has not sufficient power or force to produco a rapid natural evaporation of water from the exhaling surfaces.
Report of the Committee appointed to get cut and prepared Sections of
Mountain-Limestone Corals for the purpose of showing their structure by means of Photography. The Committee consists of JAMES
Thomson, F.G.S., and Professor HARKNESS, F.R.S. In our Report of last year we gave in detail the probable additions to our present list of fossil corals from the Mountain Limestone.
During the past year we have had several hundred specimens cut. Although many of these have been more or less spoiled, and their internal structure crushed and broken to such an extent that their specific characters cannot with any degree of certainty be made out, yet many of them reveal important structural characters which will enable us to add both genera and species to those before indicated. Many of the specimens cut have wellpreserved calices, which will enable us to figure and describe both their internal structure and external aspect, with a degree of certainty hitherto unknown.
Although much progress has been made, we are convinced that many other facts will be revealed by further investigation; and we hope the Committeo will be reappointed in order that we may continue this important inquiry.
We have not added any additional photographic plates to those exhibited last year at Liverpool. We were desirous of getting as large a number of specimens cut as the sum at our disposal would permit, in order that wo might select the most characteristic generic forms for further plates.
At Liverpool we indicated that we were in the hopes of reproducing the most delicate structures by another process, which would be more serviceable for the purpose of publication. In this we are glad to state that we have been successful. By a simple process we are enabled to transfer the details of both genera and species to copper plates, from which any number of copies can be reproduced, of which we will avail ourselves when we are ready to publish in extenso. (Two plates so prepared were exhibited.)
We have placed in the British Museum and the Hunterian Museum of Glasgow duplicates of a number of the cut specimens which have already been described; other duplicates will be sent when they have been described and named.