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mouth. In this genus great voracity is exhibited, as may be imagined, from the quantity of other rotifers and objects of various kinds often seen in the stomach at the same time. The body of the Asplanchna and its integuments are very transparent, and the stomach usually yellow or brown, so that the little creatures are easily seen in a bottleful of water lucky enough to contain them. They afford excellent illustrations of ciliary stomach-currents. The whole stomach appears lined with cilia, and they produce, by a somewhat violent action, remarkable whirlpools amongst the particles of food. Conochilus will show the same thing in a less striking way. It is not so voracious, the cilia are more delicate, and the stomach not so filled with hard matters capable of turning the currents out of their path. Powers of at least 600 or 700 are necessary to see these phenomena well, and they require careful illumination. The ciliary currents in the stomach in Asplanchna are shown in the plate. The stomach-currents are plain

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in many of the Brachions, and their existence may be demonstrated with powers of about 200 to 250.

From the digestive apparatus we may proceed to the water-vascular system, which is probably, as before stated, respiratory and excretory. It consists of delicate bands or tubes, to which, in most cases, "vibrating tags" are attached. This system of apparatus is connected with the contractile vesicle popularly called a "heart," though no physiologist now considers it to be an organ of blood circulation. The annexed diagram shows the water-vascular system of Notommata aurita, as represented by Mr. Gosse ("Trans. Mic. Soc.," 1850). The stomach and other organs are not shown in this drawing.

In

Asplanchna I have noticed the tags, as shown in the accompanying plate, Fig. 5. They were ciliated at their ends, and exhibited a flickering motion in the direction of the dark line; and this was probably occasioned by an internal cilium like that which Prof. Huxley describes in Lacinularia.

I can only very briefly advert to the reproductive apparatus of rotifers. It has already been mentioned that the males of those species in which they have been discovered (about thirteen or fourteen) have but a brief existence. Mr. Gosse -to whom we owe most of our knowledge of them-could never preserve one alive for more than twenty-four hours. They are unlike the females in appearance, as well as in the absence of digestive organs, and they contain patches of opaque matter, which is white by reflected, and black by transmitted light. Mr. Gosse was so fortunate as to see one emerge from an egg of Brachionus pala, and was struck with its differing from the ordinary offspring of that creature.

The ovary of the female rotifer is remarkably conspicuous and of peculiar shape in Asplanchna, looking like a long cushion, bent in a more or less horse-shoe form. In the Plate, Fig. 1, the ovary is shown, and Fig. 3 is a portion of it magnified 1000 times linear, showing the germinal vesicles from which the eggs arise. In Asplanchna the internal apparatus has plenty of room, and is extremely moveable. When everything is in its usual position, the large stomach is seen hanging to the gullet, while the Ovary bends like a horse-shoe, and partially surrounds it.

The nervous system of rotifers is probably simple, but as yet imperfectly made out. In Brachionus a large cerebral ganglion is seen easily behind the beautiful red eye; and in Lacinularia, Prof. Huxley describes a "bilobed homogeneous mass, resembling in appearance the ganglion of Brachionus, and running into prolongations below; but whether continued into cords or not he could not make out.”

Many rotifers exhibit some symptoms of intelligence, as when the common rotifer goes groping about, or the tubedwellers incline their heads towards particular objects. The Metopidia acuminata has a curved organ like half a pickaxe attached to its head, and works about with this, raking amongst rubbish, and selecting what it requires, somewhat like a French chiffonier with his hooked stick. If a number of Brachions are put in a vessel they soon come near each other, perhaps deriving some pleasure or advantage from the action of each other's whirlpools; but we must beware lest we ascribe too much purpose to movements which may be the involuntary results of circumstances, and it is curious that Mr. Gosse observed a Melicerta making and depositing her pellets, when her tube was broken, and she could place none where they could be of use.

The localities in which rotifers are found are chiefly in fresh and salt water, though some can live in damp moss. Some attach themselves to plants, others swim freely, and others lurk in sedimentary deposits. I have found the

common rotifer in a slime which forms on the cotton thread of a Mason's Hygrometer, where the supply of food must have been exceedingly small. They get into the cells of certain mosses, into the tubes of confervæ, and Mr. Gosse described in "Mic. Trans., 1850," a form of Notommata (parasitica), inhabiting the sphere of Volvox globator.

The rank to be assigned to rotifers, or rather their place in the animal series, has been warmly discussed-most physiologists coinciding with von Siebold and Huxley, by whom they are associated with the worms, or rather with that portion which Mr. Huxley designates Annuloida. He says, "the terms of resemblance are these:-(1.) Bands of cilia resembling and performing the functions of the wheel organs are found in Annelid, Echinoderm, and Trematode larvæ. (2.) A water-vascular system essentially similar to that of the rotifers is found in Monacious Annelids, in Trematodes, in Turbellaria, in Echinoderm, and perhaps in the Nematoidea. (3.) A similar construction of the nervous system is found in Turbellaria. A somewhat similarly armed gizzard is found in the Nemertida, and the pharyngeal armature of a Nereid larva may well be compared with that of Albertia. (5.) The intestine undergoes corresponding flexures in the Echinoderm larvæ. There are, therefore, no points of their organization in which the rotifer differs from the Annuloida."

It is an interesting question whether any of the rotifers possess true-jointed limbs. Mr. Gosse says of Dinocharis"This genus is remarkable for possessing true joints in the foot; not merely telescopic inversions of the skin, but permanent articulations with swollen condyles resembling those of the antennæ of a beetle. This fact helps to indicate that this class of animals has its proper affinities with the Articulata, which has been denied by most naturalists."

Should, which seems probable, the rotifers retain the place assigned to them by Siebold and Huxley, their relations with other groups as pointed out by Mr. Gosse are nevertheless very likely to be strengthened by further investigation.

DESCRIPTION OF PLATE.

1. Side view of Asplanchna Brightwelli, showing stomach with two egg-shaped glands, the ovary and large restingegg, magnified 80.

2. The jaws, magnified 240.

3. Portion of ovary, magnified 100.

4. Stomach currents, magnified 1000.

5. Portion of water-vascular system with tags: the dark lines down the tags represent internal ciliary action, magnified about 1000.

STANDARDS OF WEIGHTS, MEASURES, AND
COINAGE.

BY JOSEPH NEWTON.

LAST year saw carried into effect certain recommendations in reference to the above-named subject, which had been earnestly made and frequently reiterated many years previously. By virtue of an Act of Parliament, which received the Royal assent, on the 6th of August, 1866, the custody of the Imperial standards of length and of weight, together with all secondary standards of weights and measures, all balances, apparatus, books, documents, and things relating thereto, and of the Trialplates for testing the purity of the coin of the realm, was transferred from the office of the Exchequer to the Board of Trade. The change of arrangement thus ordered to be made was in all respects a remarkable one, for it disturbed a system which had existed from the days of William the Conqueror, when the Exchequer Court formed part of the well-known Aula Regia.

The actual transfer of the custody of the standards, etc., and the determination of his powers and duties connected with them were reported by the Comptroller-General of the Exchequer on the 31st August, 1866, to the Treasury. The same communication made reference, also, to the speedy transfer of the coinage trial-plates to the Board of Trade. Thus the Exchequer was quietly denuded of important duties associated with it from a remote period of English history, whilst a great amount of extra responsibility was imposed upon its more modern and, it must be added, more active successor, the Board of Trade. It would be interesting to trace the annals of the Court of Exchequer from its origin to its partial demise, but it is no part of our present purpose to do so.* We have no intention either to say one word in disparagement of the venerable institution, or of those who filled offices in it. It is, nevertheless true that for many years past the Court of Exchequer, which had charge and care of the national standards of length, weights, and measures, paid no attention whatever to their exactitude. The legislature, and not the Exchequer, must be held accountable for the neglect, for in reality there existed, up to last year, no legal authority whatever for verifying the standards. They had remained, therefore, exactly

Those who wish to obtain authentic and quaint information of the early history of the Exchequer are referred to the "Dialogus Scaccrario," written by Richard Fitz-Nigel, Treasurer to King Henry II., and printed at the end of Madox's "History of the Exchequer."

as they were constructed in 1824, plus certain alterations made in them by climatic influences, and the hand of time. Oxidation and other deteriorating powers were, of course, not idle, and the standards suffered accordingly. It was nobody's business to attend to their periodical verification, and nobody did attend to it. Hence, the fountains of justice, as it were, became tainted at the source, the so-called standards were no standards at all, and the primary instruments upon which depended (by comparison) the accuracy of all subsidiary weights and measures of the United Kingdom were false guides-blind leaders of the blind. Even in 1853, when new theoretical standards of weights and of length were legalized and promulgated, no comparisons of the old material standards were instituted. It may seem passing strange that such an omission should have been permitted, but it is for us at present simply to record it as a fact, without further comment.

From these premises it will be readily conceded that the reformatory movement of last year was not made one moment too soon, and, doubtlessly, the interests of the public will be largely promoted by it. There now exists in connection with the Board of Trade, and, of course, subordinate to it, a distinct branch, known as the Standards Department, with an efficient staff of officers, and all necessary appliances, for the express purpose of verifying and maintaining in exact order the imperial standards, primary and secondary, of Great Britain and Ireland. To ensure and facilitate the comparison and verification of provincial, colonial, and local, with and by aid of the master standards, the abolition of all fees and of the stampduty payable hitherto for the operations, has been decreed. At the head of the new department, the office of which is in Old Palace Yard, Westminster, is Mr. H. W. Chisholm, whose title-a very appropriate one-is that of Warden of the Standards. Under his energetic and practical guidance it is tolerably certain that the important duties of the whole department will be zealously and efficiently performed, and that the standards will shortly be in as perfect a condition as such arbiters should be in the first commercial nation of the world.

In fact, the Warden has, during his first year of office, just closed, evinced a considerable amount of activity, and caused thereby many valuable improvements as compared with the compulsory "let-it-alone" system of the Exchequer.

His

A perfect standard is only found in nature, and is, therefore, immutable; but a measure is variable at the will and pleasure of man. In France, a standard of length is found in the 400,000,000th part of the earth's circumference, which is equal to 39,370 English inches, and is known as a metre. In England, the philosophical standard of length is a pendulum, vibrating seconds in the latitude of Greenwich, and this is, by a law of nature, invariable. From this standard comes the yard and all other measures of length.

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