The mature Ovum of Myxine.—The earliest description of the mature ovum is that given by Allen Thomson, in the article “Ovum” in Todd's Cyclopædia of Anatomy and Physiology, vol. v., published in the year 1859. He says:—“I have found that in the Myxine glutinosa the globular yolk is enclosed in a horny capsule of similar consistence and structure (to that of Elasmobranchs), but of a simple elongated ellipsoidal shape; and in place of four terminal angular tubes there are a number of trumpet-shaped tubular processes projecting from the middle of the two ends, which probably serve the same purpose as the differently shaped appendages of the ova of the shark and skate.” He gives a figure in woodcut of the ovum, and of one of the threads magnified. The figures are correct with this exception: in the representation of the entire ovum the yolk is represented in outline as though seen through the envelope, and is globular, like the yolk of Elasmobranchs. In the Myxine ovum the yolk fills the cavity of the ellipsoidal envelope. It is not true that the terminal processes are tubular. I have examined them, and found them solid, and, as far as can be seen with a low power, homogeneous. I have not been able to ascertain from what specimen or specimens the description of Thomson is taken, but there is a single specimen of the ripe ovum in Professor Turner's museum which may have been examined by Thomson. This specimen was brought to the museum in the time of Professor Goodsir, but it is not possible now to ascertain whether it was dredged from the sea-bottom or taken from a pregnant female.

Etectro-Chemieal Reactions between Metals in fused Salts.—The present communication contains some results of a furthur study of electrical reactions at high temperatures in fused salts.

The interchanges of electro-chemical position between such metals as platinum and copper and platinum and iron in fusing salts, noticed by the author, led to an investigation as to the effect on the metals of varied intensified temperature in different parts of the same fusing salt.

In October 1881 I published in the Quarterly Journal of Mathematics (xviii. pp. 110–149) a “List of Writings on Determinants,” which contained the titles of all the books, pamphlets, memoirs, magazine articles, &c, which were then known to me to exist on the subject of the Theory of Determinants. The list consisted of 489 entries arranged in chronological order, the first date being 1693, and the last 1880. During the three years which have elapsed since it was published, I have been steadily making manuscript additions to it, not merely in the way of continuation for the purpose of keeping it up to date, but also by the intercalation of omitted titles unearthed in the course of my own researches, or brought to my notice by obliging correspondents.

The object of the following experiments, which were suggested by Professor Chrystal, was to determine the relative values of the intensity of the horizontal component of magnetic force, due to a current flowing in the coils of the Helmholtz galvanometer, for different parts of its field.

The following paper is an account of a preliminary experiment performed in the Edinburgh University Physical Laboratory, with the view of determining the thermal conductivity of ice.

The following note was written at the instance of Sir W. Thomson. It is directed mainly to one extremely important point connected with the Kinetic Gas Theory; and is designed to show to the ordinary reader the nature of the investigation, and of the real evidence for the result, without the imposing array of symbols which is usually marshalled in papers on that Theory.

After seeing in the course of one of Sir W. Thomson's lectures an experiment showing the contraction which takes place when a solution of common salt is mixed with water, I resolved upon making a number of experiments with a view to noting the result of mixing various solutions.

Owing to the kindness of the India Rubber, Gutta Percha, and Telegraph Works Company of Silvertown, and especially of their engineer-in-chief, Mr Robert Kaye Gray, I was enabled to accompany their expedition for laying the telegraph cable between Cadiz and the Canary Islands. It consisted of two steamers belonging to the company, the “Dacia” and the “International”; and I was allotted a place and all facilities for working on board the “Dacia,” where Mr Gray had charge. I joined the expedition at Cadiz on 3rd October 1883.

This paper is the outcome of 12 months' private spectroscope building, two months' observing therewith, and ten months' computing and graphical presenting of the observations. The result is a Solar Spectrum map, extending through so many as 60 double quarto plates, but capable of being arranged for the cheapest photolithographic reproduction, in a manner very easy to examine, convenient for reference, and yet at the same time affording at every point new and severe tests for its degree of accuracy.

The paper which I have the honour of presenting to you to-night is similar in construction to those I have previously brought under your notice on the For and Madi Tribes.

The Waganda are very different from the tribes further north, and a description of them will I think aptly illustrate the very marked contrasts presented by the various Central African Tribes.

This paper forms the first half of Part I. of a research into the minute anatomy, physiology, and development of Patella vulgata. The paper aims at giving a complete account of this form in both its physiological and morphological aspects. It treats, first of all, with the external features and rough anatomy. The epidermal system is then treated in detail. Some interesting modifications of the superficial epithelium are described. The epithelial cells are usually elongated columnar, with processes connecting them with a dense subepithelial layer of connective tissue. The attachment of the circular muscle is covered with modified epithelium, the epiblast cells not being absent in that region, as is said to occur in the case of the adductor muscles of Anodon. The modified epithelium at one spot near the base of the tentacle functions as an eye. The cells are there pigmented, and the cuticle is modified so as to form a double layer, with intervening trabeculae. The retinal epithelium springs from a nerve plexus, which is supported by a mesh-work of connective tissue fibres, with large lacunas.

The Atmometer is merely a hollow ball of unglazed clay, to which a glass tube is luted. The whole is filled with boiled water and inverted so that the open end of the tube stands in a dish of mercury. The water evaporates from the outer surface of the clay (at a rate depending partly on the temperature, partly on the dryness of the air) and in consequence the mercury arises in the tube. In recent experiments this rise of mercury has been carried to nearly 25 inches during dry weather.