moved sluggishly. Now and then a slight convulsive movement of the body and limbs was seen. It became weaker and weaker, until the breathing was imperceptible, and only by touch could I be certain it was not dead. Urine ran from it. At a few minutes before 12 o'clock it died. I did not see it die, but I had examined it about ten minutes before I found it dead. There was no rigidity, but the usual enlargement of the pupil was very marked immediately after death, which took place 49 hours after the administration of the poison.

The bladder was found distended with urine, and the lower bowels full of hard fæces. The smaller intestines were empty, but not tense or contracted. The gall bladder distended with bile, and colouring the stomach yellow. The lungs pink. The right side of the heart. gorged with dark blood, and the veins also; the left side contained a little thin red blood. The body was opened very shortly after death.

The experiments I have detailed show the four forms of poison extracted from Urechites suberecta to be practically identical in their physiological action. In mice they cause muscular paralysis, respiratory difficulty, and convulsions ending in death. In cats, large and moderate doses always produced vomiting, which (in the cases where very speedily fatal doses were exhibited) was followed by convulsions and death; but where death was delayed, both fæces and urine were evacuated, the vomiting frequently renewed, pulse and respiration quickened, notably the former, and muscular paralysis gradually developed, the end being preceded by convulsions. Very small doses produced on the first day vomiting, defecation and micturition; the vomiting persisting for several days, but the bowels becoming confined and the secretion of urine apparently lessened. But perhaps the most marked symptoms following the exhibition of small doses, was the refusal of all food for many days, and the great disinclination to muscular exertion. Salivation was also sometimes produced by the injection of very small quantities of the poison.

In the four experiments on cats, in which but o gr. of the poison was administered daily, there was no vomiting, indeed no visible effect for many days; then a gradual loss of appetite and general dulness, succeeded by sudden convulsions, followed in a few hours by death. In Experiment XIV, however, no symptoms of poisoning appeared for eleven weeks, and then they preceded death by less than twenty-four hours.

The smallest quantity of the pure crystallized poison which proved fatal to a cat was gr., injected subcutaneously in one dose-see Experiment XX. This was equivalent to one two-and-a-half millionth of the cat's weight. The next smallest fatal dose is that recorded in Experiment XIII, in which eleven separate doses were administered, amounting in all to gr., or one three-and-a-quarter millionth of the cat's weight. In other experiments no fatal effect resulted until three

to six times as much, proportionally to the weight of the animal, was swallowed.

The Society then adjourned over the Easter Recess, to Thursday, May 2.

May 2, 1878.

Sir JOSEPH HOOKER, K.C.S.I., President in the Chair.

The Presents received were laid on the table, and thanks ordered for them.

In pursuance of the Statutes, the names of the Candidates recommended for election into the Society were read from the Chair as follows:

:

John Gilbert Baker, F.L.S.
Francis Maitland Balfour.

Rev. Thomas George Bonney, M.A.
Prof. James Henry Cotterill, M.A.
Sir Walter Elliot, K.C.S.I.

Rev. Canon W. Greenwell, M.A.
Thomas Hawksley, C.E.
John Hopkinson, M.A., D.Sc.

John Hughlings Jackson, M.D.
Lord Lindsay, P.R.A.S.
Samuel Roberts, M.A.

Edward A Schäfer, M.R.C.S.
Herman Sprengel, Ph.D.
George James Symons.
Charles S. Tomes, M.A.

The following Papers were read:

I. "On the Life-History of a Minute Septic Organism: with an account of Experiments made to determine its Thermal Death Point." By Rev. W. H. DALLINGER. Communicated by Professor HUXLEY, Sec. R.S. Received March 26, 1878.

[PLATES 8, 9.]

Nearly four years since, in examining an infusion of animal matter, which had, unfortunately, been diluted with water, and had vegetable substances placed in it, I observed a minute and intensely active organism, which, on closer and more careful examination, I found to be of a form entirely new to me. I therefore determined to endeavour to discover its life-history; but the diluted infusion was unsuited to it, and in the course of five days no living form remained. During this time I had been able to determine very little that was consecutive, but had seen enough to lead me to desire to find it again; and for the two following years I steadily examined, all the infusions within my reach, as well as all probable places besides, but in vain. And it was

not until the latter part of the summer of 1876 that I found it again. It appeared then, in a maceration, in which the body of a vole was decomposing. The maceration was only three weeks old, and this organism had evidently only just arisen; it increased daily in vigour and numbers, and in three weeks I was at liberty to study it continuously.

For this purpose I employed the "continuous stage," jointly devised for preceding researches,* by means of which a drop of the infusion could be kept under examination, without evaporation, for an indefinite time, and with the most powerful lenses.†

My method was to follow out, as far as possible, the morphological details separately; and then to steadily follow one form from its earliest to its most mature condition; thus discovering how the different states were related, and making out an unbroken life-history. Most of the more difficult and delicate work was done with an entirely new lens, made specially for me by Messrs. Powell and Lealand; and which is nominally a 3th inch lens. It was made specially for this class of investigation, for which it is admirably adapted. Its "working distance" is sufficient; its "penetration," for such a power, is extremely great, its angle being moderate; and its "definition is as sharp and clear, when properly used, as that of the finest 4th or th. I also had the advantage of the use of the four new lenses made on a 66 new formula" by the same makers, viz., a th of low angle and great penetrating power; and a th, th, andth of high angles. I also used theth and th lenses.

One of the difficulties attending the study of this organism was its extreme rapidity and caprice of movement. Its normal form is depicted at fig. 1, Plate 8. It is there magnified 3,000 diameters. Its sarcode is clear, and to all the lenses employed structureless. It is usually found to have minute vacuoles scattered through it. The form of the body is distinctive. Its greater part is a long oval slightly constricted a little above the middle. But from the front, or shorter portion, a kind of neck (a, fig. 1) protrudes, from which proceeds the front flagellum, which is extremely fine, and from one and a-half times to twice as long as the body. Below this and at the sides or 66 shoulders" of the organism, two other long and fine flagella arise, proceeding backwards, as seen at b, c, ibid. In addition to this, there is always a nucleus-like body slightly to one side of the lower part of the organism, as seen at d; and with the higher lenses and delicate manipulation there was frequently seen, within this, an ex

Vide "Further Researches into the Life-History of the Monads." Monthly Micro. Journal, vol. xi, pp. 97-99.

+ Linen instead of bibulous paper is now used as the agent for conveying a constant supply of evaporating moisture to the chamber in which the organisms are examined in this piece of apparatus.

tremely minute globule, also indicated at d. But as this was not always present, even in the normal state of the organism, it was probably not important.

The extreme length of the body was the th of an inch. It rarely exceeded this and was often less.

It swam, as I have said, with great rapidity; and all its movements were most graceful, varied, and controlled. Its usual mode of motion is in a direct line, or in curves; and with its trailing flagella behind and its active anterior one, it is a very remarkable object. But the suddenness with which it can arrest its most rapid movement, or change it in any direction up, down, or directly reversed, is still more remarkable. In this the flagella at the sides are brought into active operation; sometimes both being spread out like long arms; at other times one being stretched out and in vigorous action, while the other is closely pressed to the other side, and so forth, giving this organism a control over its movements which is of extreme interest. Indeed the apparent volitional mastery which this seemingly structureless speck exercises over these equally structureless filaments, for the determination of its course, cannot be seen and studied without wonder.

But besides this free-swimming movement, it was capable of the most vigorous motion in an "anchored" state. Most of the larger septic organisms belong to, or are associated with, certain conditions of the decomposing matter; and disappear before the advent of other forms, when that condition is past. This one was associated with the general breaking up of the decomposing animal matter; and the movement which I am about to describe apparently contributed to this. It was a powerful springing motion. The trailing flagella became attached to the floor as at a, b, fig. 2, by what means could never be discovered; but the attachment was very secure and conld be discontinued at any moment. Directly the anchorage is made, the two anchored flagella with the utmost rapidity coil in a spiral, as at c, fig. 2, bringing the body of the organism nearly to a level with the floor. With equal suddenness it darts up in the line indicated by the arrow d, and thus having reached the limits of its flagella it moves down, with equal rapidity, in an arc of a circle of which the flagella are the radius; indicated by the arrow e. In this way the whole body is brought down on the point f. But the matter to be noticed is, that this is never done except upon a fragment of the decomposing tissues in the infusion. And if a small fragment be taken out at any time and examined, it would soon be encircled by thousands of these forms incessantly darting up and down upon it in the way described; and careful observation showed that they, by this means, rapidly changed the form and diminished the size of the little particles so attacked. No morphological changes are at all apparent in those that

are in this condition, but they are continually freeing themselves and swimming away and others are constantly coming.

The changes now to be described will be understood to be given as the result of long-continued and repeated effort. Failure is very much more frequent than success in working out the preliminary details, but pre-eminently so in steadily following to the end the changes undergone by a minute organism. I merely record the final results, which have issued both from the study in detail of phases in the life-cycle of the organism, such, for example, as the minutiae of the method of fission and fusion-and also from an unbroken observation of its comparatively short life-cycle, which was three times repeated.

Following then, steadily, a normal form, which has just freed itself from the springing condition, as fig. 1, the first real indication of change, though by no means the first to be discovered, is a splitting of the anterior flagellum, as seen at a and b, fig. 3, and the moving of the nucleus to the centre, as seen at c. With a power of from three to four thousand diameters, there may also be seen a delicate line under the base of the flagellum, as shown at d. In the course of from thirty to sixty seconds this has widely opened and the base of the flagellum has divided as seen at a, fig. 4, while at the same time the nucleus shows an incision in the direction of its length, as seen at b in the same figure; and a similar incision has commenced at the posterior end of the body, as shown at c. In a very few seconds more, this slight incision (c, fig. 4) is the origin of a wide opening, as seen at a, fig. 5, above which it will be seen that the nucleus has almost divided and a pale line runs through the body-substance from the upper to the lower opening. The posterior opening widens much more rapidly than the anterior one, as fig. 6 shows, depicting a condition ensuing in from one minute to four minutes after that shown in fig. 5. And at this stage the nucleus has split into two and the divided parts occupy distinct positions, as shown at a, b. The upper or anterior split now widens as well as the posterior one, as shown in tig. 7, leaving the two parts merely united by a neck of sarcode.

*In fact hundreds are followed which from one or more of many causes do not complete the cycle of their lives. It may be arrested—and frequently is—by death in the earlier stages, in the middle, or still worse towards the end. In the same way there may be failure by the individual form being lost amidst a crowd of others, or by slowly working its way to the little ring of liquid at the edge of the "cover,” and then going out into it, and so making further study impossible. Or the apparatus may be at a critical moment a source of trouble; the delicate balance between the moisture carried over by capillarity, into the chamber containing the fluid with its organisms, and the evaporation taking place, may by some means, such as a sudden change of temperature, be broken, and nullify hours of patient and, but for that, successful work. In every such case there is but one method open-it is to begin again de novo upon another form.