of the diatom when free. The mechanism has not yet been publicly demonstrated, however, although some few microscopists have had the good fortune, under very exceptional circumstances, to see (or fancy they saw) external protoplasmic movements. The communications on this subject to the different scientific journals are, as is usual when the subject is in the non-verifiable stage, very dogmatic and contradictory. Still the homogeneous-immersion lens of high power should be the means of determining the cause or causes of the movement.

Our Journal has been made more valuable during this year by the publication of the very careful and intelligent researches of Messrs. Morris and Henderson on Trichophyton tonsurans. They describe the life-history of the fungus from the sowing of the spore to the branching of the resulting filaments on the sixth to eighth day. Moreover they describe the aerial hyphæ and fructification. Remarking on the difficulties of determining the botanical position of the ringworm fungus, on account of the frequent development of adventitious fungi, Messrs. Morris and Henderson endeavoured to obtain a medium which should possess perfect sterilization and should have sufficient consistence to retain spores in a fixed position for continuous observation. They came to the following conclusions, illustrating their paper by photo-micrographs (employing a 1/5 in. object-glass of Beck and an amplification of 1000):-That the spores of Trichophyton tonsurans grow freely on the surface and in the substance of gelatine peptone at from 15° and 25° C. That the mycelium only will grow in the substance of the jelly, and that the hyphae require air to produce conidia. That the branching, septa-formation, and fructification are identical with those of Penicillium. That the spores of the second generation reproduce ringworm on the human skin. That outgrowths resembling resting spores appear on some of the filaments.

The red mould of barley has been most carefully examined and illustrated by Mr. C. G. Matthews, F.C.S., and published in one of the parts of the Journal. The common coloured mould seen at the germinal end of the corn was grown on a large scale by breaking up germinating barley with a little water into paste. Very fine silky tufts of the red mould were thus obtained from 1/2 to 3/4 in. in length and nearly 2 in. in diameter. Much of the red colouring matter was diffused amongst the plasma and the hyphae were tinged with it, where they sprang from the nutrient surfaces, though their extremities were colourless. The hyphæ gradually became interlaced and flattened down as a mass and a kind of sporulation began to be noticed, and pseudo-spores-very minute bodies-came from the threads. They did not appear to develope. Shortly after the flattening of the hypha, a pink dust

was seen here and there on its whitish surface. This consisted of clusters of crescent-shaped spores. They appear to sprout from the extremities of short hypha. From these crescent-shaped bodies, which are spores, fresh growths of the mould could be obtained by sowing on a suitable surface. The red colour is the matter surrounding the crescent-shaped spores. The mould holds its own against other kinds, and sooner or later swellings occur in the threads of the hypha and on sporangia. The contents discharge with the application of water, and the spherical spores were sown, and they reproduced the red mould." The author described a similar mould on the melon.

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I speculated in my last address regarding the future of research into the life-history of bacilli, and the results of the work on this subject during the past year have been really most wonderful. Dr. Ransom condensed the breath of phthisical patients and obtained bacilli, rendering them visible by what may be called the Gibbes process. He found that they were indistinguishable from those found in the sputa and in tubercle. It is not reassuring to know that bacteria exist in vast multitudes in the soil, but M. Miquel has shown that at Montsouris an average of 750,000, in the Rue de Rennes 1,300,000, in the Rue Monge 2,100,000 germs exist per gramme. Brautlecht mixed baked sand, gritty earth, and tolerably loamy garden mould with liquid containing bacteria, and covered the mixture with a bell-glass. few hours after, there were a great number of micro-organisms in the vapour condensed under the bell-glass, and of the form of those contained in the liquid. The sprinkling of dry sand over the earth diminished the number of organisms. It is comforting to read that while rain is falling, the number of the bacteria in the air is sensibly diminished; it increases, however, when the ground dries, and diminishes with ten to fifteen days' drought. Miquel states that at Montsouris, the average number of bacterial germs per cubic metre of air is 142 in autumn, 49 in winter, 85 in spring, and 105 in summer. The same author states that the number of germs in hospitals is vast, amounting in the summer months to an average of 5600, and in the autumn to considerably over 10,000 per cubic metre of air.

The sensitiveness to light of Bacterium photometricum is accompanied by more remarkable properties, for these organisms accumulate in media in positions where the invisible ultra red rays of the spectrum penetrate. The influence of light on the development of bacteria has been shown in the instance of Bacterium termo to be remarkable. Direct sunlight kills bacteria, diffused sunlight does not; but this statement has to be qualified, for Jamieson discovered that temperature has to do with the matter, and that at moderate and low temperatures direct sunlight does no

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harm to the organisms. Direct sunlight and air, by drying up bacteria, destroy them. Some bacilli, those of anthrax for instance, which exist in serous matter from anthrax tumours, may be dried at a temperature of 32° C. 89° 6 F., and then exposed to 100° C. = 212° F. It is stated that not only do the organisms resist heat, but become able to resist antiseptic agents. They do not, however, appear to act as definitely as before, but they produce modified anthrax. Following on these results, those of M. Chauveau are very interesting. He mixed a sterilized infusion of meat with the blood of cattle disease, and placed the mixture first in a temperature of 42-43° C., and then to 47° C. It appeared subsequently that although the vital activity of the bacillus was not interfered with, its capacity for acting as a disease-producer was destroyed.

One of the most suggestive observations on bacteria has been that which indicates that they act as starch and diastase in the absence of other carbon nutriment, and that the action on starch is effected. by a ferment secreted by them, and which like diastase is soluble in water, but precipitable by alcohol. This ferment acts as diastase, changing the starch into a sugar capable of reducing cupric oxide, but not possessed of peptonizing properties. It is to be hoped that after all this searching after bacteria and after these recondite experiments have been conducted over again, that some definite study of the bacteria of a locality where such diseases as ague prevail will be undertaken. The whole history of the disease points to a bacterian origin, and there should be no difficulty in examining the secretions with a view of thoroughly investigating the organism.

A paper lately read before the Royal Society proves that solution of quinine is fatal to certain bacteria, even to those of phthisis, and the well-known influence of that drug over ague should stimulate therapeutists to investigation.

There have been two communications to the Society on special methods of preserving delicate organisms for the use of the Microscope, which are of exceptional interest and value. Mr. Lovett has explained his intelligent method of using what he properly calls a judicious admixture of various proportions of alcohol, glycerine, and water to Haentsche's fluid, which consists of alcohol absolute 3 parts, pure glycerine 2 parts, and 1 part distilled water. Limnocodium Sowerbii, the wonderful medusoid which, living in fresh water at 85° Fahr., is such a marvel so far as its origin is concerned, has become preservable, thanks to Mr. Squire's weak solution of bichloride of mercury. There is no doubt that this medium will be further employed. Mr. Saville Kent has suggested the use of weak solutions of potassic iodide for preserving infusoria, and Mr. Waddington has contributed a paper on the use of tannin in showing infusoria.

It is a matter of great congratulation that the Society maintains its character at home and abroad as a useful and truly scientific institution. There is no doubt that great progress has been made in microscopical science during the last few years and that the communications read before this Society, the recorded debates and their influence on our large and increasingly important number of Fellows have assisted in this satisfactory state of things. The Society may take the credit of having now completely eradicated the old and very erroneous notions regarding what was called "angular aperture," and of having disseminated and established the knowledge of aperture in its correct signification and the use of the "numerical aperture" notation. The first term has, indeed, almost ceased to be employed by advanced microscopists. The homogeneous-immersion principle has been developed and the media which have been proved to be so valuable have originated with Fellows of the Society and have been recorded in the Journal.

I feel a sensation of some pride that I should be able to hand over the presidency of this Society in the midst of its useful and prosperous career to an observer of the highest class of excellence, whose success has been assured by the employment of the instrument which has been largely perfected by the intellectual and mechanical gifts of Fellows of this Society. I may, I trust, (without the least desire to stop the particular physical and mathematical tendencies of many of our Fellows) urge the great number of good observers of nature amongst us to be stimulated by the very valuable reports of the researches on the structures of the invertebrata and plantæ, which appear in the Journal-a compendium of which the Society may justly be proud-to undertake work which may come before their future President and receive his criticism. In fact it may be hoped that that excellent Journal will contain more records of the labours of the Fellows of the Society.

In the proceedings of all great Societies there are occasions when congratulations and the desire for future usefulness have to give place to very opposite expressions. Men toil and pass away, and others enter into their labours.

The present occasion is no exception to the rule. We have to deplore the loss of three great practical opticians, two of them being microscopists of the highest renown. One had attained an age far beyond that which is usually noticed amongst men who have laboured with head and hand, and on looking back at his life it must be admitted that by his means an immense amount of intellectual pleasure was given to the world, and a great amount of exact knowledge has been consolidated.

For fifty years the name of Powell has been a household word

amongst microscopists, and now it remains only to the sons of the late Mr. Hugh Powell. The distinguished man whose name I have just mentioned was amongst the first of the Fellows of this Society, and long before the year 1840, he had become celebrated for his microscope-stands and lenses. His name will always be remembered as that of a designer and maker of first-class high-power objectives, and as a conscientious maker of the ordinary powers. The following obituary notice has been already published, and it expresses the merits of Mr. Powell :

"In 1834 he was awarded a silver medal by the Society of Arts for a stage for a Microscope.' In 1840 he succeeded in making an achromatic object-glass of 1/16 in. focal length, which the late Professor Quekett, in his treatise on the Microscope, stated was 'the first that had been seen in this country'; and in 1841 the Society of Arts awarded him a silver medal for his mode of mounting the body of a Microscope.' Mr. Powell was the first optician in England to construct object-glasses on Amici's 'immersion' system. A 1/25 in. was made by Mr. Powell in 1860, a 1/50 in. was perfected in 1864, and a 1/80 in. in 1872. The more recently developed formula of the homogeneous immersion' system was the subject of special attention on the part of Mr. Powell and his brother-in-law and partner, Mr. Lealand, but failing health compelled him to rely upon the efforts of his son, by whom objectglasses on this formula having the highest apertures on record have been constructed. Mr. Powell was among the earliest on the roll of Fellows of the Society at its foundation in 1840."

Microscopical science has also to deplore the death of a very able and most distinguished practical optician in the United States. Mr. Robert B. Tolles has left a name in America and Europe which will always be mentioned with respect. He was a skilled objective-maker of the first class, and like most men of his mental and artistic calibre was a quiet and unassuming gentleman. Tolles was always ready to avail himself of discoveries and seized at once upon the value of the lenses with large numerical apertures, and he also speedily availed himself of the improvements of the homogeneous-immersion principle. He was not, as one of his friendly biographers states, entitled to the credit of showing the practicability of this system. It was Amici, Stephenson, and Abbe, as I stated in my first Presidential Address, who established the homogeneous-immersion system. Tolles, however, developed the apertures of high-power objectives and produced admirable results, being the first to manufacture combinations of lenses of high amplification and suited to the immersion system in America.

The last obituary notice relates to Henry Dallmeyer, who was so well known in the sister sciences of astronomical and photographic optics. Mr. Dallmeyer left Germany in 1849