The pathway of these reflexes is imperfectly known; the sensory branch appears to communicate by means of collateral and reflex neurons (long reflex arc) with the entire motor sphere.

In unilateral lesions interrupting the pyramidal tract the cutaneous reflexes are frequently diminished, while the tendon reflexes are exaggerated.

The cremaster reflex, or contraction of the cremaster muscle following irritation of the inner surface of the thigh, and the abdominal reflex, contraction of the abdominal muscles at various levels (upper and lower reflex), elicited by stroking the skin of the abdomen, are of very little clinical significance, so far as we know. Both reflexes appear to be absent in focal cerebral lesions on the side opposite to that of the diseased focus, while in multiple sclerosis they are often absent on both sides.

The conjunctival reflex consists in closure of the lids when the conjunctiva is touched. It is absent in paralysis of the trifacial and facial nerves.

The palpebral reflex consists in closure of the lids when an object is suddenly brought close to the eye; it is absent in lesions of the optic nerve and in facial paralysis.

The pharyngeal reflex consists in a choking movement following irritation of the mucous membrane with a brush; it is absent in paralysis of the vagus and spinal accessory. The palatal reflex effects contraction of the palate after

contact.

2. The Periosteum and Tendon Reflexes.—(a) The patellar tendon reflex is the most important. By tapping the patellar tendon while the muscles of the legs are relaxed, a contraction of the quadriceps is induced, the patient's attention being diverted by pressing his hand or separating his folded hands. If the contractions are vigorous, the leg is jerked forcibly upward. The patient should sit on the edge of a chair, with the entire sole of the foot on the floor and the leg slightly extended.

The intensity of the reflex varies widely within physio

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logic limits in various individuals. Exaggeration of the reflex occurs in neurasthenia, in lesions of the central motor neuron (inhibitory fibers in the pyramidal lateral tract), in irritation of the reflex arc (meningitis, tetanus, neuritis), and in exhausting diseases. The reflex is abolished when the reflex arc is interrupted (tabes, crural neuritis, anterior poliomyelitis, myelitis in the lumbar enlargement), in coma, in epileptic attacks, and in recent injuries of the spinal cord, probably as a result of irritation of the inhibitory fibers. (See foot-note, p. 93.)

The Achilles tendon reflex is subject to the same variations as the knee-jerk. It consists in twitching of the muscles of the calf when the Achilles tendon is tapped. When this reflex is exaggerated, it produces the not unusual phenomenon of ankle-clonus, elicited by forcible flexion of the foot on the leg. The more important of the periosteal and tendon reflexes in the arm are the following:

Radial and ulnar periosteal reflex, elicited by striking the styloid process of the radius or ulna; and the triceps tendon reflex, elicited by striking the tendon above the olecranon.

In addition to the reflexes mentioned, the masseter reflex should be tested. It consists in a movement of the lower jaw, elicited by striking against a piece of wood applied to the lower jaw. The clinical significance of this reflex is not very great. The pathologic alterations that occur are subject in general to the above-mentioned principles.

3. The Pupillary Reflex.—The following varieties are distinguished:

(a) Reaction to light, or contraction of the pupil by the action of the sphincter muscle when the same eye is illuminated (irritation of the optic nerve).

(b) Consensual reaction to light, which follows illumination of the other eye.

(c) Reaction of accommodation or contraction of the pupil in accommodating the eye to near objects; really a secondary movement.

(d) Converging reaction; of little clinical significance. The contraction is proportionate to the tension of the rect. med.

The reaction to light should be tested for each eye separately, so as to exclude consensual reaction. If hemianopsia is present, each half of the retina should be tested separately. It is best to use the ophthalmoscope, but for ordinary purposes it is enough to cover the eyes with both hands and then to remove one hand quickly.

Before examining the eyes it is well to determine whether the pupil is abnormally dilated or contracted. Dilatation (mydriasis) occurs in atropin and cocain poisoning, blindness, coma, epileptic convulsions, paralysis of the oculomotor, and other conditions. Contraction (miosis) occurs in morphin poisoning, tabes, paralytic dementia, meningitis, affection of the first dorsal segment, iritis, etc. Inequality in the pupils, which occurs in paralysis, tabes, meningitis, and other conditions, should not be

overlooked.

The reaction to light may be abnormally sluggish or altogether lost when the reflex arc is interrupted, as in blindness due to disease of the optic nerve, in oculomotor paralysis, or in lesions of the reflex collaterals (tabes, paralytic dementia) in the corpora quadrigemina. It is also observed in coma, narcosis, and during epileptic convulsions, but not in hysteria.

In lesions of the optic tract there is hemianopic pupillary rigidity when the blind half of the retina is illuminated.

IV. Examination of the Functions of the Bladder and Rectum.

(a) Lesion of the Central Pathways (Myelitis Dorsalis, Focal Diseases).-In lesion of the motor path there is retention of the urine and of the alvine discharges; voluntary evacuation is interfered with. If the bladder is distended, there is dribbling of urine.

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Lesion of the sensory paths destroys sensation in the bladder, and hence the desire to urinate, retention resulting.

(b) Lesion of the peripheral pathways and of the bladder center (reflex collaterals in the sacral portion of the cord) produces incontinence of urine and of the alvine discharges; also sphincter paralysis (lesion in the lumbar and sacral region or chorda equina), and constant dribbling of urine. The reflex contraction of the sphincter ani, which can be felt with the finger and which is present in central disturbances, is absent.

In addition to these paralytic phenomena there may be irritative symptoms of a reflex or central character, such as constant desire to urinate, tenesmus, strangury.

Vesical disturbances are very likely to result in cystitis (secondary inflammation, polionephritis, and pyemia, conditions which always threaten a patient suffering from spinal disease).

V. Examination of Trophic and Vasomotor Disturbances.

Trophic disturbances occur in lesions of the anterior horn, in neuritic processes, and in diseases of the bloodvessels, etc. The most important symptoms are redness, swelling, cyanosis, abnormal pallor, urticaria-like eruptions of the skin, erythromelalgia (painful swelling of the hands and feet occurring in paroxysms), and multiple cutaneous edema. Atrophy of the skin or glossy skin, scleroderma, atrophy of the skin on one side of the face (hemiatrophia facialis); anomalies in the sweat secretion (hyperhidrosis, unilateral sweating in hysteria and neurasthenia).

Idiopathic gangrene of the extremities occurs in Raynaud's disease, syringomyelia, and in Morvan's disease; bed-sores (in paraplegia) are only indirectly due to nervous influences. Perforating ulcer in tabes (chronic ulcer in

the toes); alterations in the joints, arthropathies; swelling, thickening, and hypertrophy in tabes, etc.

VI. The Examination of the Psychic Functions.

1. Speech and Writing (Aphasia and Agraphia).(a) Disturbances of the Articulation (Dysarthria). By this term is meant a disturbance of the speech in the peripheral pathway. There may be inability to pronounce the individual letters clearly, the pronunciation may be nasal or guttural and altogether unintelligible, accompanied with great straining of the muscles of the mouth and tongue. This occurs in bulbar diseases, in lesions of the hypoglossus and facial nerve, in malformation of the muscles used in speech, absence of palate, etc. Among special varieties are the typical bulbar speech, nasal speech (rhinolalia), and slow speech (bradylalia). Scanning speech occurs in multiple sclerosis. Halting speech, or dysarthria literalis, includes various defects in the speech, especially in the power of forming letters.

Stammering is due to abnormal spastic contractions of the muscles of speech, of central origin. Stammering is aggravated in moments of psychic emotion, while halting speech is improved. In disturbances of the articulation the labial, dental, palatal, and nasal sounds are tested separately.

(b) Aphasia.-Aphasia is always due to a central lesion. It may be cortical (the focus is in the cortex), transcortical (destruction of the association fibers), or subcortical (interruption in the motor pathway from the center to the periphery),

a. In motor or ataxie aphasia the patient is unable to say anything, but understands everything that is said to him (lesion at II, Fig. 13, consult p. 41).

If the patient is unable to say a single word of his own accord, there is total motor aphasia. If he is still able to say a few words, such as "yes" and "no," the condition is known as monophasia