liquid; and this, from the facility with which it absorbs oxygen, quickly assumes a blue colour under exposure to air from the reconversion of the cuprous into the cupric oxide.

If ammonia be added to the ordinary Fehling's solution, a liquid is obtained which is rendered colourless by boiling with a sufficiency of sugar to effect the complete reduction of the cupric oxide present to the state of suboxide. As the saccharine product is dropped in the blue colour gradually fades, without any occurrence of precipitation to interfere with the perception of the precise moment when the point of complete decoloration is attained. The ammonia exerts no interference with the process of reduction, but simply dissolves the reduced oxide, leading, when complete decoloration is effected, to the production of a perfectly colourless, limpid liquid.

Enough ammonia must be present to secure that the suboxide is held in solution, and precaution must be taken that whilst the analysis is being performed the reduced oxide does not become reconverted into the oxide by exposure to the air. To obviate this the operation should be conducted in a flask instead of an open capsule.

The appliance that naturally suggests itself as most suitable for employment is a flask of about 80 cub. centims. capacity, with a cork inserted into the neck, through which a delivery tube from a Mohr's burette, graduated in tenths of a cub. centim., passes for dropping in the product to be examined. Through the cork, also, there must be an exit tube for the escape of air and steam from the flask. Should it be desired to avoid the impregnation of the surrounding atmosphere with ammonia, the exit tube may be connected by vulcanized tubing with a U-shaped tube containing fragments of pumice stone moistened with water or a weak acid. The burette being fixed in the stand, the flask is allowed to hang suspended, so that there may be nothing to obstruct the full view of its contents. The heat is applied by means of the flame of a spirit lamp, and the best position for watching the disappearance of colour is by the light reflected from a white background specially provided for the purpose. It is convenient to have another burette, graduated in cub. centims., and of 100 cub. centims. capacity, fixed in the stand for holding and delivering the ammoniated copper solution. Messrs. Griffin, of Garrick Street, have constructed an arrangement adapted to meet the requirements.

I at first took it for granted that in the action occurring the same relation existed between the amount of oxide of copper reduced and that of sugar oxidised, as under the employment of the copper test in the ordinary way, viz., that 5 atoms of oxide of copper were reduced by 1 atom of sugar, and the liquid I first employed was prepared by adding to 100 cub. centims. of Fehling's solution 300 cub. centims. of strong solution of ammonia (sp. gr. 880) and 600 cub. centims. of distilled water. The liquid thus made contained one-tenth of

Fehling's solution, and if it comported itself in the same manner as the latter, 10 cub. centims. of it would stand equivalent to 005 grm. of grape sugar. In working with this liquid the results obtained were so accordant in relation to each other that I had no misgiving about its uniformity of action; but I felt that before being definitely accepted they ought to be checked against known amounts of sugar. The accomplishment of this proceeding, however, is not altogether unattended with difficulty, on account of the uncertainty of obtaining grape sugar free from impurity and in a perfectly dried state.

The method I have adopted has been to operate upon weighed amounts of cane sugar and produce inversion by boiling with an acid. I first found that the cane sugar, which is sold in coarse colourless crystals that which is known as "white crystal," and used for sweetening coffee-stood the test on examination for purity with Laurent's polarimeter. A weighed quantity was taken, and, after being inverted by boiling with hydrochloric acid, the acid neutralised, and the liquid brought to a known volume, subjected to treatment with the ammoniated copper liquid. Repeated trials were made with varying quantities, and it was found that the results stood in harmonious relation to each other, but that the amount of sugar indicated was larger than the calculated amount of invert sugar from the weighed quantity of cane sugar taken. At first I was at a loss for an explanation of this result, but subsequent observation has revealed that in the case of the ammoniated liquid, 6 atoms of oxide of copper are appropriated by 1 atom of sugar, instead of 5, as in that of Fehling's solution used in the ordinary way. When the reckoning is made upon this basis the results exactly correspond with the actual amount of sugar known to be present. Moreover, with solutions of ordinary grape sugar and diabetic sugar, examined comparatively with Fehling's solution used in the ordinary way and the ammoniated copper liquid, the results exactly accord under the reckoning that 5 atoms of oxide of copper are appropriated in the one case and 6 atoms in the other by 1 atom of sugar.

To be quite satisfied upon this point, a large number of observations under varying conditions have been made, and whilst what I have stated holds good for the ammoniated copper liquid prepared from Fehling's solution, without any further addition of alkali, and with the addition of potash to the extent of 1 grm. to 20 cub. centims. of the ammoniated test, yet a larger quantity of potash alters the action, and with 5 grms., and anything beyond, the behaviour is brought to the same as that of Fehling's solution used in the ordinary way, viz., 5 atoms only of oxide of copper are appropriated by 1 atom of sugar. With quantities of potash between the 1 and 5 grms., the results stand between the 5 and 6 atoms of cupric oxide.

I may mention that observation has further shown that whilst

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 and allowed to boil for a few minutes in order to get rid of the presence of air. 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.

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.

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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