generalised epileptic spasm induced in the limb by cortical excita

tion.

6. Differentiation of parts of the nerve roots by the degeneration method, in which connexion an allusion is made to certain results obtained by the author, which do not accord with the Wallerian law of degeneration, and which are in accord with the experiments of Joseph.

From the results of these various methods of experimentation, the author draws the following conclusions:

I. Stimulation Experiments.

1. The compound movement obtained by stimulation of a whole nerve root is a well-coordinated one, depending on the action of a group of muscles in synergic combination, as Ferrier and Yeo showed to be the case in the monkey.

2. This compound effect may be resolved into its component factors when it is found that movements diametrically opposed to each other may be represented in the same nerve root, e.g., flexion and extension.

3. Such single simple movements bear a constant relation to the nerve roots, the same movements being always found in any given root, and thus such movements always bear the same relation to the spinal level; e.g., flexion of the elbow is always represented one root higher than extension of the same joint.

4. Fibres representing a certain movement always preserve the same position in a given nerve root; e.g., extension of the wrist is represented by a bundle of fibres in the upper part of the circumference, while flexion is represented by a bundle of fibres in the lower part of the same root.

5. Each bundle of nerve fibres representing a single simple movement in a nerve root remains distinct in its course to the muscle or muscles producing such a movement, without inosculating with other motor nerve fibres.

6. The group of muscles supplied by any given nerve root occupy both the anterior and posterior surfaces of the limb. In other words, muscles whose unimpeded action would produce one movement are represented in the same root as others whose action would produce a movement diametrically opposite.

7. In such combinations certain muscles are always more extensively represented than others, so that, with a current sufficiently strong to stimulate all the fibres of a nerve root equally, certain muscles predominate in their action over others.

8. The muscles whose action predominates in one root always predominate in that root.

9. If the muscles producing flexion of a certain joint predominate

in their action in one root, those producing extension predominate in another.

10. It is possible, by stimulation of a single bundle of fibres in a nerve root, to produce contraction of a single muscle, and it alone. 11. The same muscle is always represented in more than one nerve root, usually two, and to an unequal extent in these.

12. When the same muscle is represented in two nerve roots, the muscle fibres innervated by one root are not innervated by the other.

II. Ablation Experiments.

1. Division of any given nerve root produces paresis of the group of muscles supplied by it.

2. This paresis is only temporary, and soon passes off almost completely.

3. Such division of a nerve root does not result in incoordination of the remaining muscular combinations represented in other nerve

roots.

III. Exclusion of a certain Root or Roots during an Epileptic Spasm in the Limb (the root being divided at the time, and not some time previously).

1. Division of one or more nerve roots produces alteration of the position of a limb during an epileptic spasm, which altered position depends on the particular muscular combinations that have been thus thrown out of action.

2. No incoordination is produced in the action of the remaining muscular combinations.

3. There is no evidence of overflow of the impulses which ought to travel down the divided root into other channels through the spinal centres, so as to reach the muscles by new paths.

IV. Degeneration Method.

1. These experiments confirm the anatomical facts that had been previously ascertained by dissection, as to which nerve roots supply any given nerve with fibres.

2. The degeneration which results in the nerves is not a scattered one, but is localised to distinct bundles of nerve fibres occupying a certain position in the transverse section of the nerve.

3. The Wallerian law of degeneration is found to be erroneous with regard to the degenerations which result on division of a nerve root on the distal side of the intervertebral ganglion; for not only is degeneration found in the peripheral end of such a root, but also in that portion of the sensory root between the ganglion and the spinal cord;

pointing to the probability that there are certain nerve fibres which do not depend on the ganglion for their trophic supply, but derive the same from elsewhere, either the spinal cord at another level, or the periphery.

In conclusion, the author calls special attention to the value of the method of excluding one or more nerve roots during an epileptic spasm, as affording a means of confirming the facts that have been previously observed from stimulation of the nerve roots, and also of aseertaining new facts with regard to them and the plexuses which they form. He further goes on to point out that it supplies a valuable means of studying the manner in which conduction of impulses from the cortex through the nerve roots and plexuses to the muscles takes place; and that it is capable of still wider extension, as if, instead of producing general epilepsy, less powerful stimuli be applied to the centres for different movements, as represented in the motor cortex, it will afford a means of connecting such centres, or parts of these, with the nerve roots to which fibres proceed from these cortical motor centres.

III. "The Influence of the Kidney on Metabolism." By J. ROSE BRADFORD, M.D., D.Sc., Fellow of University College, London, Assistant Professor of Clinical Medicine at University College, Grocer Research Scholar. Communicated by Professor SCHÄFER, F.R.S. Received February 18, 1892.

(From the Physiological Laboratory of University College, London.)

The results described in this preliminary communication were obtained in a series of experiments commenced in June, 1889, and at present still in progress, with the object of elucidating the functions of the kidneys, and to gain an insight into the disturbance produced in the economy by disease of these organs.

Method.-All the experiments were made on dogs, and a complete experiment involves the following stages:

:

Firstly. The animal, after being weighed, is placed in a suitable chamber, and fed on a weighed diet containing a known quantity of nitrogen; the water drunk is also measured. The amount of urine passed is measured, and the quantity of urea and total nitrogen in it determined. Finally, the weight of the fæces and the amount of nitrogen in them are also determined. All the nitrogen determinations were made by means of Kjeldahl's method; the urea was estimated by the hypobromite method. A daily determination of the above factors was made for a period of a week, and a daily average

thus obtained. In the earlier experiments only the quantities of urine and urea passed were determined. On removal from the chamber, the animal is again weighed.

Secondly. The operation described below is performed on one kidney. After recovery from this, the dog is again placed in the collecting chamber, and the above data again obtained for a week or more.

Thirdly. The second kidney is removed, and the animal again placed in the collecting chamber, the food and excreta being again determined for a period of a week or more.

Fourthly. At a variable time after the second operation the animal is killed by bleeding, and the amount of nitrogenous extractives present in the tissues determined.

As regards the operative procedures, there is nothing to remark about the second operation-the kidney is removed in the usual manner by lumbar incision; a few words are necessary in order to describe the first operation. After anesthetising the animal with chloroform and morphia, the kidney is exposed by a lumbar incision and freed from its connexions. The vessels in the hilus are then compressed with the fingers, the kidney transfixed from before back, and a large wedge of kidney substance, with the apex of the wedge at the pelvis of the kidney, removed from the middle of the organ. The piece removed weighed from 5 to 15 grams in different cases. The very free hæmorrhage is arrested by ligature of the large vessels divided, and by pressure on the cut surface. When all bleeding had been arrested (the vessels in the hilus being of course no longer compressed) the cut surfaces of the kidney were brought together by two or three silk sutures passed in deeply, and by numerous superficial fine horsehair sutures involving only the cortex and capsule of the organ. The abdominal wound was closed and dressed in the usual

manner.

Full antiseptic precautions were always used, and morphia was given hypodermically to prolong the narcosis.

Summary of Experiments.—Twenty-three animals survived the first operation fifteen animals survived both operations.

Thus, eight animals died after the first operation and before the second. The causes of death in these eight were as follows:—

In four cases the animals were accidentally killed with chloroform administered to perform the second operation. In two cases the wound became septic and the animals were killed. In one case death resulted from hemorrhage on the seventh day, and one dog, to which further reference will be made below, died of asthenia thirty-six days after the first operation.

This communication deals with the results obtained in the fifteen complete experiments. In one, the first, no observations were made on the urine, and in three dogs the observations were incomplete, so

that there remain eleven cases in which observations were made on the urine before and after the operations.

Effects of the First Operation (i.e., the removal of a wedge of the kidney substance).—The shock of the operation passes off in about twenty-four hours, but for two or three days there is some hæmaturia, and the appetite is poor. The temperature of the body remains at its normal height, or there may be slight pyrexia. The dog, however, soon regains its former health, and no permanent ill effects result from the operation in the great majority of cases. In one case (one of the eight incomplete experiments) the animal died thirty-six days after the operation, with considerable wasting and loss of appetite, and nothing was found post mortem except extreme atrophy of the kidney operated on. The opposite kidney was healthy and of normal size. The atrophy was very marked, as the following numbers show:-7.6 grams of the left kidney were removed, post mortem the remaining fragment of the left kidney weighed only 3.5 grams, and the opposite kidney 18 grams. In this case, the only one where death resulted from the effects of the first operation, although the atrophy was very marked, there was microscopically no evidence of cirrhosis, and no lesions of the renal vessels were discovered. The cause of death is obscure, as the second kidney was not removed.

With this one exception, the first operation failed to produce any serious or permanent ill effects, and the only result noticed was slight emaciation, but this was generally recovered from in a week or two.

A period of from one to six weeks was allowed to elapse between the first and second operations, and during this time the animal was placed in the chamber, and the ingesta and excreta determined. following table gives the results observed in five cases :

The