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glucose prepared from starch behaves like other varieties of grape sugar, there is an intermediate product formed before the completion of the process of conversion, which behaves in a different manner from invert sugar, grape sugar, and sugar of diabetes. Estimations made with the ammoniated copper liquid coincide with those made with Fehling's solution without the presence of ammonia, and the addition of potash to the ammoniated liquid produces no modification of the result.

In order that the ammoniated copper liquid may be brought to the same standard of sugar value as Fehling's solution, and it is desirable that this should be the case, the proportion of copper must be increased so as to give 6 atoms against 5. By taking 120 cub. centims. of Fehling's solution, 300 cub. centims. of strong ammonia (sp. gr. 880) and making up to a litre with distilled water, the proper proportion is obtained, and the ammoniated liquid gives results corroborated in accuracy by the balance, and coinciding with those obtained by Fehling's solution employed in the ordinary way.

As a minor point it may be remarked that the diluted state presented by the ammoniated liquid offers an advantage by diminishing the liability to error arising from any want of absolute precision in

measurement.

Twenty cub. centims. of the ammoniated copper solution, corresponding with 010 grm. sugar, having been run in from the burette containing the test, the flask is adapted to the cork attached to the delivery tube of the other burette containing the saccharine product for examination. The flame of a spirit lamp is then applied underneath, and the contents of the flask brought to a state of ebullition boil for a few minutes in order to get rid of the The saccharine product is now allowed to drop from the burette until the blue colour of the test is just removed, and a perfectly colourless limpid state produced.

and allowed to presence of air.

On account of the ammoniated copper solution used being only equivalent to 2 cub. centims. of Fehling's solution, it is necessary that the product to be examined should not be in too concentrated a form. For delicate observation it is convenient that the dilution should be such as to require the employment of from about 10 to 20 cub. centims. to decolorize the 20 cub. centims. of the ammoniated copper solution.

The ammoniated copper solution enjoys the advantage of possessing a self-preservative power. It is well known in the case of Fehling's solution that, in the course of time, not only does the liquid become impaired in stability, but actually reduced in strength, by the spontaneous deposition of a certain amount of suboxide. Not so, however, with the ammoniated liquid. Here the conditions are such that under exposure to air the copper cannot fail to remain in solution and

to be maintained in a fully oxidized state. A further advantage is given by the influence of the presence of ammonia on the colour of the test, for, in proportion to the height of colour of a volumetric liquid, so is its degree of delicacy as a reagent, and the effect of the addition of ammonia to the ordinary copper test is to considerably increase the blue colour belonging to it.

Seeing that the test here proposed acts with equal efficiency either in the presence or absence of extraneous organic matter, it is alike adapted for employment by the chemist, the physiologist, and the medical practitioner in relation to diabetes.

IV. "On the Effect of Strong Induction-Currents upon the Structure of the Spinal Cord." By WILLIAM MILLER ORD, M.D., F.L.S., Fellow of the Royal College of Physicians, Physician to St. Thomas's Hospital. Communicated by J. SIMON, C.B., D.C.L., F.R.S. Received December 17, 1878.

(Abstract.)

The results of a series of experiments are related. They were founded upon considerations offered by chorea, tetanus, and similar diseases; certain clinical facts and post-mortem observations having led the author to suppose that the occurrence of protoplasmic convulsion or spasm in the grey matter of the nervous system was consistent with the morbid appearances and with the history of cases.

The present series of observations was made upon adolescent dogs. The spinal cord was the part selected for experiment. The dogs were killed by chloroform, and the cord, rapidly exposed, was galvanized for different periods and in different directions. In all cases parallel experiments were made with dogs of the same age and size, all points of the operation being carried out in the same way, save for the application of the galvanic currents.

The following effects were observed:
:-

1. Broadening of the cord in parts through which currents had been passed longitudinally, narrowing where transverse currents had been applied.

2. In the narrowed parts a great diminution in the sectional area of the grey matter with retraction of the posterior horns.

3. In the same parts a remarkable dilatation of the central spinal canal, and an infiltration of myelin and leucocytes into the cavity.

4. The production of spaces around corpuscles, vessels, and nervebundles by the retraction of the protoplasmic matter. Such spaces were often found filled with débris, containing coagula, myelin, and vacuoles. They corresponded in appearance with the "perivascular erosions" of Dickinson.

VOL. XXVIII.

U

5. The contraction of nerve-corpuscles, which, being much more marked between their branches, gave them a scalloped appearance. Vacuoles were formed within them, and in the spaces formed by their retraction, and by the retraction of surrounding parts.

6. In some places rupture of nervous tissue was observed.

7. In longitudinal sections nerve-fibres were found flattened and varicose, the flattening resembling that described by Elischer in fibres of median nerve in chorea.

Conclusions.-1. That, in young dogs, the protoplasmic constituent of the grey matter contracts en masse under the influence of strong faradaic currents.

2. That it contracts unequally and irregularly by reason of its unequal and irregular sectional area, causing thereby condensations at certain points-notably in the anterior horns and around the central canal-and rarefaction at others-notably in the middle of each crescent; such rarefaction going on sometimes to rupture of tissues.

3. That nerve-corpuscles contract in various degrees according to the strength and duration of currents, and that while they tend in contraction to become spherical they also tend to become vacuolated.

4. That the vessels are in some places strongly contracted and empty; in others dilated and filled with blood clot, having the appearance of embolus.

5. That the appearances correspond so decidedly with appearances in chorea and tetanus as to give ground for the supposition that contractions, such as are produced by electricity, do actually occur during life under the effect of nervous shock, and may be phenomena causal or associate of disease.

V. "Concluding Observations on the Locomotor System of Medusa." By GEORGE J. ROMANES, M.A., F.L.S. Communicated by Professor HUXLEY, Sec. R.S. Received December 30, 1878.

(Abstract.)

The principal bulk of the paper is devoted to a full consideration of numerous facts and inferences relating to the phenomena of what the author terms "artificial rhythm." Some of these facts have already been published in abstract in the "Proceedings of the Royal Society" (vol. xxv), and to explain those which have not been published would involve more space than it is here desirable to allow. The tendency of the whole research on artificial rhythm, as produced in various species of Medusa, is to show that the natural rhythm of these animals (and so probably of ganglio-muscular tissues in general) is due, not exclusively to the intermittent nature of the ganglionic

discharge, but also in large measure to an alternate process of exhaustion and restoration of excitability on the part of the responding tissues the ganglionic period coinciding with that during which the process of restoration lasts, and the ganglionic discharge being thus always thrown in at the moment when the excitability of the responding tissues is at its climax.

Light has been found to stimulate the lithocysts of covered-eyed Medusa into increased activity, thus proving that these organs, like the marginal bodies of the naked-eyed Medusa, are rudimentary organs of vision.

The polypite of Aurelia aurita has been proved to execute movements of localization of stimuli, somewhat similar to those which the author has already described as being performed by the polypite of Tiaropsis indicans.

Alternating the direction of the constant current in the muscular tissues of the Medusa has the effect of maintaining the make and break stimulations at their maximum value; but the value of these stimulations rapidly declines if they are successively repeated with the current passing in the same direction.

In the sub-umbrella of the Medusa waves of nervous excitation are sometimes able to pass when waves of muscular contraction have become blocked by the severity of overlapping sections.

Exhaustion of the sub-umbrella tissues-especially in narrow connecting isthmuses of tissue-may have the effect of blocking the passage of contractile waves.

Lithocysts have been proved sometimes to exert their ganglionic influence at comparatively great distances from their own seats-contractile waves, originating at points in the sub-umbrella tissue remote from a lithocyst, and ceasing to originate at that point when the lithocyst is removed. A nervous connexion of this kind may be maintained between a lithocyst and the point at which the waves of contraction originate even after severe forms of section have been interposed between the lithocyst and that point.

When the sub-umbrella tissue of Aurelia is cut throughout its whole diameter, the incision will again heal up, sufficiently to restore physiological continuity, in from four to eight hours.

January 23, 1879.

W. SPOTTISWOODE, M.A., D.C.L., President, in the Chair.

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

them.

The following Papers were read :—

I. "Researches on Chemical Equivalence. Part I. Sodic and Potassic Sulphates." By EDMUND J. MILLS, D.Sc., F.R.S.. "Young" Professor of Technical Chemistry in Anderson's College, Glasgow, and T. U. WALTON, B.Sc.

October 16, 1878.

Received

The conception of a chemical equivalent as employed in these researches corresponds to a definition first given* by one of us, viz., that the chemical equivalent of a body is that weight of it which does the unit of work. We do not therefore use the term in its ordinary sense; as, for example, when it is said that H is "equivalent" to Cl, Na, &c.

The following experiments were arranged with the view of determining the effect of potassic and sodic sulphates on the rate of formation of ammonia, when nascent hydrogen is made to act on potassic nitrate. Judging from their behaviour in other cases, it was expected that in this instance, also, their action would be one of retardation. Experiment, however, has proved the reverse, on the whole, to be true.

The extremely delicate nature of the reaction, which is liable to be spoiled by the accidental falling in of a single speck of dust, or by slight variation of temperature, or unequal exposure of the different solutions to light, rendered the attempt to measure the effect a matter of peculiar difficulty.

At first, common sheet zinc, thoroughly cleansed from grease, was placed in a solution of potassic nitrate and hydrate, and the amount of ammonia formed during periods varying from twenty-four hours to one week was measured. But the results were very irregular and unsatisfactory. Galvanic couples seemed to be established at certain points on the surface of the zinc, probably due to the presence of iron or lead as impurities. Thin zinc foil was next tried, but with little better result; neither were any alterations in the shape or disposition of the foil attended with success. Fresh experiments were also undertaken with sodium amalgam instead of zinc and potassic nitrate; but the action, though rather more uniform, was still very uncertain. It was found impossible to obtain a perfectly homogeneous solution of sodium in mercury, entirely free from sodic oxide and hydrate; and this seriously impaired the accuracy of measuring out the amalgam.

The only plan which was found to give results at all comparable with each other, was using zinc amalgam and potassic nitrate. The experiments were performed in wide-mouthed glass-stoppered bottles of cylindrical shape, having an internal diameter of 60 mm., and a total capacity of 315 cub. centims. Each bottle contained 1 grm.

* "Philosophical Magazine," [5], i, 14.

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