by the knowledge we have acquired from practical observation, and perhaps had best be put aside.

From these physical conditions of body there does not seem, then, great cause of danger under chloroform. There are some who say that asthenia and enfeebled heart should be added to conditions of danger. I have never seen any sound evidence in support of this view, and Snow would never entertain it. "If," he maintained, "a patient is considered sound enough to bear an operation, he is certainly sound enough to bear chloroform." Dr. Sansom has also a very good observation on this point. He remarks that "persons who are in health and are about to be subjected to some minor operation are put under chloroform with more difficulty " -and he might truly have added with more danger"than those who by long illness and suffering are resigned to their fate, and who, prepared to meet the worst, have, to some extent, lost the sense of fear." Few better observations of a practical kind have ever been made.

Apart, however, from specific detectable conditions, there is a general condition of body, a condition of nervous excitability, which is unfavourable to an extreme degree. Persons of nervous lymphatic temperament are sometimes met with who have no special conditions. of disease, but who feel shock from everything more easily than the rest of mankind, and who are "distilled to jelly" by the act of fear from comparatively slight causes. These are in danger before ever they inhale a full breath of the vapour of chloroform, and we might say of them that they would die under the impression produced by any anæsthetic whatever did we not know that some other gases or vapours-nitrous oxide gas, for the most striking example—are breathed by them, up

to insensibility, with impunity. These consequently are unduly susceptible to vapour of chloroform, and die, as we know too well in some unhappy instances, from the smallest effective portions of the vapour. Here we may say we have a condition of danger that is knowable; and when I come to the consideration of the phenomena of death from chloroform it will form an important subject of study.

CONDITION OF SURROUNDING AIR AS A CAUSE OF DANGER.

The condition of the air in respect to moisture and temperature is of great moment. In the first place, if the air be surcharged with moisture at any temperature the introduction of the narcotic vapour into the blood and the condensation of the vapour in the blood will be impeded, and the stages or degrees of narcotism prolonged. In like manner recovery from the narcotism after the vapour is withdrawn is slower in a moist than it is in a dry air. And, lastly, if in an air saturated with moisture there appear during administration any symptoms of failure of the circulation, the danger is much greater than it would be were the air dry, since with failure of the circulation and loss of radiation from the open moist surfaces of the body there is a quick condensation of fluid, and accumulation of fluid upon open surfaces. The cold sweat which settles on the face when a person faints is not the sweat of natural excess of water thrown off by the body, but is the water, which ought to pass off naturally by the skin, condensed on the skin. The sound people commonly call the "death-rattle" means the same phenomenon-the phenomenon of accumulation

*These are the susceptible persons I have classified as belonging to the Morituri (see ASCLEPIAD 24, Vol. VII., pp. 1-20).

of water in the air-passages, from cooling. Under chloroform there is a natural tendency to reduction of animal temperature, and during exhaustion under chloroform this reduction is most pronounced. Hence, unless the air be dry, the accumulation of fluid on surfaces like the bronchial and vesicular surfaces of the lungs is a ready process, and the mischief which may follow, trifling as it may appear, is most serious.

The observation herewith made has been forced upon me often in experiments for the resuscitation of animals after the cessation of respiration under chloroform. In setting up artificial respiration I have sometimes found the operation so free and so effective, I have wondered at the result as much as the lookers-on. In other cases in setting up the artificial respiration I have found the operation at once impeded, and even rendered abortive, by nothing more nor less than the presence of water in the air-passages. In such cases, as we exhaust and refill the chest with air, we can hear the cause of difficulty in a moist fine bronchial râle; and, when the bronchial surface is exposed after death, the smaller tubes are found filled with frothy secretion.

As to temperature. In previous lectures I have carefully demonstrated the effect of temperature on the process of inhalation; I need not do more now than touch on the subject. Suffice it to repeat the following facts: (1) that a high a high temperature quickens the change of chloroform from the fluid to the gaseous state; (2) that it quickens diffusion in the air; (3) that it quickens the process of condensation by which the vapour is received into the blood; (4) that it quickens the narcotic action; (5) that it quickens recovery from narcotism when the narcotic is withdrawn. Concerning these points the second and third

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named are the most important to remember; in fact, they govern our knowledge on the other points. Snow constructed from his own experiments a most useful table, which is here copied. In this table it is shown that a volume of 100 cubic inches of air will have diffused through it certain given measures of chloroform vapour at certain temperatures, the air being assumed as a constant quantity of 100 cubic inches.

I have myself further shown, by direct experiment, that the rate of diffusion and of condensation of chloroform in the blood is so governed by the temperature of the air that the difference of 30° Fahr. makes a difference of six minutes in the time required for the production of the third degree of narcotism; that the second degree, the degree of muscular excitement, is greatly prolonged by a cold atmosphere, and that the danger is increased by cold.

The safest average temperature for inhalation is from 60° to 70° of Fahrenheit's thermometer. A temperature below 60° is too low; and a temperature above 70° is not too high, seeing that the circulation is best maintained, under chloroform, at high temperatures.

EPIDEMIC NEUROPARESIS.-INFLUENZA.

THE LESSON OF SYMPTOMS.

HE more closely I have watched the phenomena of what is called influenza, the more certainly I have become impressed with the conviction. that the symptoms as a whole are identical with certain of those defined and classified in my paper read before the Medical Society of London on Monday, December 12th, 1887, and published in ASCLEPIAD, No. 7, Vol. V., pp. 1-22, to which I gave the name of Pulmonary or Pneumo Paresis. At the time I wrote that paper I looked upon the conditions named as idiopathic purely, running a course less pyrexial and more prolonged than the epidemic disease which has recently been amongst us and in all parts of the world; but, as I have analysed symptoms one by one, I have been led by force of observation to the view that the only difference between the two forms of disease is that the present widely distributed disease is more rapid in its course, more speedily intense, and more diffused, because dependent on a common cause of disturbance which affects the system generally, instead of being confined to a few persons particularly predisposed to pulmonary failure. In all essentials the symptoms in the acute and extended form are the same; they start from a catarrh, and are attended, as might be expected