in the cell; but the mastax and the intestines kept moving. It remained in this state for two hours, and then began to rouse up, but instead of expanding the tentacles and making an exit out of the upper end of the cell as before, it began to back out of the cell by the lower end, and after some time cleared it, turned round, and gradually expanded the tentacles. I watched it a greater portion of the night, and it seemed in no way the worse for the operation it had undergone.

On Tuesday, 16th, 9 A.M., I found it alive and to all appearance anchored by the remaining portion of its foot, one cannot say sucker, because that had been left behind. At 10 P.M., twenty-four hours having elapsed, it was still alive, and seemed to be in the best of health in spite of the change in its circumstances. The tentacles were perfectly semicircular and rigid, which is a sure indication of health, they becoming limp and straggling when the creature is sickening or about to die.

On Wednesday, the 17th, at 7 A.M., I found the creature alive, and what is more strange, that it had thrown off an ovum in an advanced stage of development. The ovum was close to its side, but whether attached to it or not I do not know. Agitating the liquid in the trough as far as I dared did not disturb the ovum. By 11 A.M. the young Stephanoceros broke the shell and swam away, leaving the shell still clinging to the parent, where it remained until my observations came to a conclusion. At 11 P.M. (49 hours having passed) the creature was alive and well, and firmly fixed by its portion of tail, with algae commencing to form at the base. At first I took this for the commencement of a new cell, but in this respect I was mistaken, for up to the time of its death it remained in the naked condition.

Throughout the day on Friday, the 19th, the creature was wonderfully active in finding and selecting food.

On Sunday, the 21st, all through the day there were unmistakable signs of approaching dissolution. The mastax worked in a very fitful manner. I left it in the evening, feeling sure it would be dead by the morning, as was the case, just eight days from the time of leaving the cell. I had great difficulty in finding the dead body and empty case, the growth of Oscillatorieæ, &c., having for the last day or two been so great that it was with the greatest difficulty the animal and the case could be kept from being hidden.

Another fact I think worthy of noting: Examining some Anacharis, I found an empty case of Stephanoceros Eichhornii containing an ovum left by the parent. I watched it, and saw the young one break the shell, come out into the cell, and after swimming round inside it, pass out of the aperture.

The above observations will speak for themselves, not only as to the character of the cell of Stephanoceros Eichhornii, but that

it is able to live and propagate its species independently of the

cell.

On another occasion I watched the development of a young Stephanoceros from the moment of hatching, and am able to verify the fact that the tentacles originate as buds, and unroll like the fronds of ferns. After the lapse of about eleven hours from the time of hatching, the upper portion of the young animal commenced to swell, and small buds began to be pushed upwards much in the same way as the tentacles begin to show themselves on the more advanced buds of Hydra. These buds were covered with minute cilia, and when they had been pushed up a short distance they began to gradually unfold (plate V. figs. 2 and 3) in the same manner as one sees the fronds of ferns unfold. They remained in this drooping state for two days, but on the third day took the beautiful arched form of the adult.

Ehrenberg was correct when he stated that Stephanoceros Eichhornii was viviparous, although at the time his ideas were considered erroneous. I have seen them give birth to young in this way very frequently, and on one occasion Dr. English watched an individual under the same circumstances. The specimen that I watched was, when I found it, thoroughly sunk into the cell. The cell had not been retracted with the creature (fig. 1), but was perfectly erect. The creature was as I thought in a dying state, and nothing in the shape of food tempted it to come out of its cell. The posterior portion of the body was very much enlarged, and hung down like a bag. The tentacles seemed with the funnel to be thrust into the body of the creature; in fact, at times, it seemed huddled in a heap. After a short time it revived a little, and seemed inclined to elongate, but quickly retreated again. With a 1/2 in. and C eye-piece I saw the outlines of a young Stephanoceros in the pendulous portion, and later a slight opening in it through which it began to protrude head first. As it gradually came out, the posterior portion opened much wider, and the parent seemed to strain itself to get rid of its burden. At length it seemed about to do so, but the young one, as if fearful to trust itself from its mother, withdrew, but soon to be expelled by a violent effort on the part of the latter. After floating about in the cell for a short time, it made its escape in the usual way through the natural orifice. The mother never recovered, but died in the cell about half an hour afterwards.

The fact of the parent dying might at first sight seem to lead to the conclusion that this was not a true act of viviparousness, but I have, as I have said above, witnessed several similar cases, but not attended with the same fatal results to the parent.

* Resident Medical Officer at St. Mary's College, Canterbury.

I may mention here the process which I adopt in examining Stephanoceros. I take an ordinary glass slip and place the object with a small quantity of water in the centre. I then shred some blotting-paper very thin, cut three small squares and place them at different intervals round the fluid, but taking care not to let the blotting-paper touch the fluid, or else the object will be drawn towards it by capillary attraction. I usually wet the blottingpaper, previous to putting it on the slip. I mention this as I have lost some valuable specimens through inadvertence. I then place the cover-glass over the object, letting it rest on the edges of the blotting-paper; and as the fluid evaporates it is easily renewed by wetting the edges of the paper. I find twice in twenty-four hours quite sufficient. The process is very simple and inexpensive, and I have found it answer better than the usual livebox or compressorium. I have kept Stephanoceros alive thus for ten and twelve days, and have watched its progress from the ovum to maturity. What is important to any one whose means are limited, it is inexpensive, and very convenient. I keep it covered, when not under observation, with a small watch-glass.

IV.-The President's Address.

By Prof. P. MARTIN DUNCAN, F.R.S., V.P.L.S., &c.

(Annual Meeting, 13th February, 1884.)

THE two addresses which I have had the honour of delivering as your President, were mainly devoted to the consideration of the practical optics of objectives of high power. On the present occasion I desire to direct attention, amongst other matters, to the importance of the perfection and use of those combinations of lenses which do not amplify greatly, and yet are more frequently employed than high powers and quite as usefully.

The combinations which give large amplification, are doubtless very attractive to the high-class microscopist, who prides himself on overcoming the difficulties attending the employment of his objectives, and they are of course absolutely requisite in most microscopical investigations. But the low powers-so readily and easily managed, so necessary before the employment of the highpower objective is attempted, so important in the use of the binocular Microscope and of the polarizing apparatus, and such auxiliaries to the hand-lens, from the readiness with which opaque objects can be viewed-are of paramount importance to microscopists of every degree.

There are many microscopists who enjoy the use of their instruments without any desire or power to add to the original research which accumulates so seriously year by year. They like to see beautiful things, to marvel at the æsthetics of nature, to examine the intricacies and delicacies and exquisite symmetry of the structures of natural objects which so far surpass the results of the art and industry of man. To all these followers of our science the low-power objective is of primary importance. Many hundred lithographic plates are published, year by year, on which are depicted minute recent and fossil forms which could not be studied without the low-power objective, and which do not come within the scope of high amplification. As being necessary to the most advanced investigators of minute things in their preliminary work, as absolutely necessary for the draughtsman and describer of opaque and transparent small objects, and as the media of great intellectual enjoyment, the objectives which are termed low in power, from their magnifying capacity being small, and which have from 1/2 in. to 4 in. of focus, should always receive attention. They illustrate the supreme ease with which former weary labour has been superseded.

A good monocular or binocular stand, a large and movable

stage with its proper accessories, and the bull's-eye, mirror, and illumination to match, are almost invariable accompaniments of the low power. The observer can work hour after hour and with but little fatigue. The object can be drawn with or without the camera lucida; and if it is a rock specimen the polariscope can be used with ease.

It was quite another matter in days gone by, when, however, most lasting indeed everlasting-work was done with the aid of the low and imperfect powers. Compare the luxurious microscopist of to-day with the painfully labouring yet ever illustrious Swammerdam. In working at his memoir on the Day-fly, the figures in which are marvels of exactitude, Swammerdam excited the admiration and pity of Boerhaave, who wrote of him as follows: "All day he was employed in examining objects, and at night described and delineated what he had seen by day. At six in the morning in summer, he began to receive sufficient light from the sun to enable him to trace the objects of his examination. He continued dissecting until 12 o'clock, with his hat removed, lest it should impede the light, and in the full glow of the sun, the heat of which caused his head to be constantly covered with profuse perspiration. His eyes being constantly exposed to a strong light, the effect of which was increased by the Microscope, they were so affected by it that after midday he could no longer trace the minute bodies which he examined, although he had then as bright a light as in the forenoon."

But it was long after the time of Swammerdam before comfort and microscopical investigation were associated. Even after the achromatic system had been discovered and utilized, the “doublet" and "triplet" were used; but these scientific atrocities gave way to the combination of lenses now employed, and the days of comparatively easy working began. Great care was taken in the manufacture of the objectives of low power in this country, and magnificent specimens of science and art were speedily brought forth. I speak under correction, but it appears to me that there has not been any great improvement upon the low-power objectives which were produced by our great Microscope-makers a quarter of a century since. There has been an influx of second-rate low-power objectives, together with those of a high class, and the reason has been, not from any deterioration in the skill of the artizan, but from the belief, on the part of the public, that low-power objectives are more easily made than those of high power, and that therefore they should not be so costly. This is a great mistake, and the mischief produced by it, in the demand for cheap low-powers, has not been checked by the experience of those microscopists who almost entirely use objectives of a high amplification. Many investigators rarely employ a low power, and provided their high