Root.

9th Subthoracic..

Movement.

rator internus, quad. fem. and the two gemelli.

Short flexor of the digit and hallux, adductor of the hallux, interossei and lumbricales, sphincter vaginæ, obturator internus, sphincter ani.

The results of the experiments are in harmony with those of Eckhardt. Many of the muscles of the limb are supplied by three spinal roots, some by two; one alone, as far as I have yet observed, by a single root only. Individual variation is frequent. Excitation of the same spinal root not always throws into action the same muscles, even in individuals of the same species, sex, and approximate age; nor does it always produce the same movement, e.g., flexion at knee followed excitation of 5th root in two individual instances. Analysis of the distribution of the component filaments of a root shows that in different individuals filaments which correspond in absolute position in the nerve-root do not correspond in function. Nevertheless, Herringham's "Law I" (quoted above) holds good for the outflow of fibres throughout considerable regions of the cord, although a sciatic plexus of the post-axial class may occur in the same individual as a brachial plexus of the pre-axial class, so that in its narrowest sense the "law" is not always applicable to great lengths of the cord. No exception has been found to it in the sense that an efferent fibre pre-axial in one individual to some particular other efferent fibre is ever in any individual of the same species postaxial to it.

The distribution of the peripheral nerve-trunks is not obviously different, whether by its root-formation the plexus belong to the preaxial or to the post-axial class. The peripheral nerve-trunks are, as regards their muscles, relatively stable in comparison with the spinal roots. When the innervation of the limb-muscles is of the pre-axial class, so also is that of the anus, vagina, and bladder; and conversely.

The region of outflow from the spinal cord of the fibres destined for a natural group of the limb-muscles, or the representation of a particular movement at a limb joint, is often not conterminous with the origin of the filaments of a spinal root, but has its limits at points within spinal segments, either overstepping or falling short of their boundaries. Thus the outflow to the intrinsic muscles of the sole sometimes has its upper limit placed nearly midway up the region of origin of the filaments of the 6th root. The lower limit of the outflow to the calf muscles sometimes lies about two-thirds down the region of origin of the 8th root. Other examples could be cited. The ankle, knee, &c., which seem to be divisions between funda

mentally distinct portions of the limb, are not regarded as such in the segments of the spinal cord.

If the simple movements (flexion, &c.) of the limb-joints be considered individually, the region of representation in the spinal roots of Macacus extends for each into at least three segments of the cord.. The region of representation for each simple movement is about as extended for the small joints (digits) as for the large (hip-knee). The whole region of representation for the movements of the knee is, however, longer (includes more cord segments) than that for the ankle; and that for the hip is longer than that for the knee. This is because the more distal the joint the greater the overlap of the regions of representation in the roots of each of the two opposed movements at the joint. Of the opposed movements, the one which is in a direction toward the anterior aspect of the limb is always represented the more pre-axially in the spinal roots.

In the thigh, the nerve-roots supplying the musculature are none of them common at once to the muscle groups of the anterior and posterior aspects of the thigh. In the foot and leg the nerve-roots supplying the muscles each supply muscles situated both on the anterior and posterior aspects; this is more marked in the case of the foot than of the leg; yet in the former even the musculature of the sole is distinctly post-axial to that of the dorsum.

Although there is clear evidence that the nerve supply of the skin of the hallux is pre-axial to that of the 5th digit, my experiments have given only equivocal evidence that the musculature of the hallux is pre-axial to that of the minimus; nor is in the thigh the gracilis (lower part) pre-axial to the vastus externus. The mutual relationship of gracilis and vastus externus is as that of rectus abdominis to erector spinæ in the trunk, i.e., ventral to dorsal; the same is probably true of hallux and 5th digit (as regards their musculature). This is in accord with Paterson's* views of the mutual relationship of the obturator and anterior crural nerves, although not with his extension of a similar view to the relationship of the internal and external popliteal nerves.

The posterior aspect of the thigh and leg afford an important exception to the rule given by Forgue and Lannegrace, and confirmed, as regards the fore-limb, by Herringham, viz., that, of the superficial and deep muscular layers of a region of the limb, the superficial layer is innervated by more pre-axial roots than the deep layer. The reverse holds good for the calf muscles and the hamstrings.

The significance of the distribution of the efferent fibres of a spinal root is, as J. Müller suggested, anatomical (based on metamerism, &c.) rather than functional (based on co-ordinate action, &c.). Excitation of an entire efferent root produces a combined movement

* 'Jl. of Anat. and Physiol.,' 1887 and 1889.

due to the action of many muscles, but there is no safe ground for believing that the combination is of a functional character; the weight of evidence is against this.

As to the question whether a muscle, when supplied by several nerve-roots, is supplied by them in such a way that one piece of the muscle is supplied by one root, another by another, although there is certainly great interlapping of regions belonging to the individual roots, I cannot agree with Forgue and Lannegrace when they say, “Excitation of a spinal root determines in the muscles which it supplies a total, not a partial, contraction." Simple inspection is enough to convince one, that in the case of some of the larger muscles, e.g., in the thigh and spinal regions, the nerve supply from the individual roots is distinctly partial, that a district of the muscle belongs to this root, another district to that, although always with a large mutual overlap; striking examples are given by the sartorius, 3rd and 4th (Macacus) sacrococcygeus superior, 7th, 8th, 9th (cat), &c. On the other hand, as the distal end of the limb is approached, the intermingling of the root-districts in the several muscles becomes more intimate, and in the muscles of the sole the intermingling of the muscle-fibres belonging to individual nerve-roots is so complete as to baffle analysis, except by the degeneration method. In the sphincter muscle of the anus there is an overlap of the motor distributions of the right and left halves of the body. The sphincter ani is supplied by four nerve-roots, two right-hand, two left-hand. Any three of these may usually be cut through without the anus becoming patulous, or exhibiting asymmetry. Conversely, excitation of any one of the efferent roots supplying it causes contraction of both right and left halves of it. The innervation of the bladder from its right- and left-hand roots, is, on the other hand, neither in the case of its sympathetic nor its direct spinal supply of a bilateral character.

IV. "On the Causation of Diphtheritic Paralysis." By SIDNEY MARTIN, M.D., F.R.C.P., Assistant Physician to University College Hospital. Communicated by GEORGE BUCHANAN, M.D., F.R.S. Received March 2, 1892.

The paralysis following diphtheria in man is so closely associated with the acute disease that it is more correctly considered as a symptom and not a sequela. Its mode of production in man has not been demonstrated.

A chemical examination of the blood and spleen of eight patients who had died of diphtheria revealed the presence of two classes of substances not normally present in the tissues of the body, viz. (1) of

two albumoses or digested proteids, proto- and deutero-albumose, giving the same chemical reactions as the albumoses of peptic digestion, and (2) of an organic acid, which is soluble in absolute alcohol and in water, to a less extent soluble in amyl alcohol, and insoluble in ether, chloroform, or benzene. There is no base or alkaloid present. Owing to the small quantities in which this acid was obtained, a more detailed chemical examination was not possible.

Physiological Action of the Albumoses.-When injected into the circulation of a healthy rabbit these albumoses produce fever. If a single dose only be given, the fever subsides, and the animal remains apparently well for months. A single dose, however, may kill in a few hours.

Repeated doses of the albumoses, besides producing fever, cause a paralysis which may come on in two days, but more often is evident in six or seven days, and may be delayed for twenty days if the dose is small.

The total doses given were between 0.083 gram and 0·157 gram per kilo. of body weight in rabbits weighing between 1000 and 2000

grams.

The paralysis is not complete, but is a paresis, and is not accompanied by any special wasting of the paralysed parts. The paralysis is progressive, and, if the dose be large enough (over 01 gram per kilo. of body weight), the animal dies in syncope with either slow or quickened respiration.

The animals that do not die, but show paralysis, may have syncopal attacks, with an affection of the respiration; but they recover from these.

Five animals were used for experiment, and they all showed the same symptoms, including a loss of body weight, which is proportional to the dose of the albumoses.

A post-mortem examination of these animals showed that the blood was slow in coagulating with the largest doses. Bacteria were absent from the blood and tissues, and in only one case was any oedema (of the abdominal wall) found.

After staining with osmic acid and counterstaining with boraxcarmine, the nerves were found extensively degenerated, while the spinal cord, spinal ganglia, and brain were normal.

The degeneration of the nerves is what has been described by Gombault in his experiments on lead poisoning as "un névritesegmentaire périaxile," or a segmental degeneration.

This degeneration affects a segment of the nerve; the fibres at that part lose their white substance of Schwann, and the axis cylinders become attenuated, and, in many cases, ruptured. If the axis cylinder

becomes ruptured, the nerve fibre below the point undergoes the Wallerian degeneration. The early stage of the segmental degeneration is the breaking up of the white substance of Schwann.

There may be more than one degenerated segment in the nerve which may then undergo completely the Wallerian degeneration. Above the degenerated segment the nerve is normal, the change being simply peripheral and not central in origin.

All nerves in the body may be affected by this degeneration: the motor nerves, the sensory, and the visceral (sympathetic).

An example may be quoted to show the extent of the nerve change. A rabbit, which received two doses, equal to 0.1 gram per kilo. of body weight, showed definite palsy on the twentieth day, and was killed on the twenty-fourth.

Segmental degeneration was found in the following nerves :-
I. MOTOR.

The lower part of right cervical sympathetic.

The nerve change is, therefore, widely spread over the body.

Physiological Action of Organic Acid.-This is much less toxic than the albumoses, and I have not succeeded in producing paralysis with it. It, however, produces a moderate degree of nerve degeneration when injected into the circulation.