An occasional complication is severe _headache_ which may persist for a week or longer. Other complications are all exceedingly rare; paralysis of the lateral rectus muscle of the eyeball or of other ocular muscles has been recorded, and is probably due to toxic bye-products which are the result of impurity of the drug. Persistent nausea and paralysis of the bladder and rectum and even of the lower extremities have also been recorded, but are to be regarded as the greatest rareties, and probably due to impurity of the anæsthetic. Indications. Spinal analgesia may be used for any operation at or below the level of the umbilicus. Excellent anæsthesia is obtained for the operation for radical cure of umbilical hernia, but anæsthesia above this level is not so constant, and is regarded by many authorities as unsafe. The procedure is of special value in cases in which a general anæsthetic is unsafe:--(1) In old enfeebled patients suffering from strangulated hernia, enlarged prostate, disease of the female pelvic organs, and other conditions where anæsthesia is necessary below the umbilicus. (2) In patients who are already suffering, or who are likely to suffer, from severe shock. The drug has the same effect on the nerve trunks of the cauda equina as on the peripheral nerves--it causes blocking of the centripetal sensory impulses which are such a potent factor in the causation of shock. (3) In diabetic gangrene spinal analgesia is the safest form of anæsthesia to employ. Contra-Indications Children up to the age of fourteen or so are apt to be frightened, and spinal analgesia is better avoided except in special cases. It is contra-indicated also in septic conditions on account of the possibility of septic meningitis resulting from metastasis of the infection, the drug having possibly the action of lowering the vitality of the cord and meninges. In tuberculosis and syphilis it is better avoided for the same reason. It should not be used where organic disease of the spinal cord or brain is already present. Analgesia Produced by Freezing. A transient analgesia can be produced by freezing the skin. An ether spray was formerly employed, but was found to be troublesome and inconvenient. The most convenient procedure consists in freezing the part by means of a spray of ethyl chloride. This drug is supplied in a glass cylinder with a very fine outlet so that it breaks up into a fine spray as it escapes. The cylinder is held about 8 or 10 inches from the patient’s skin, and pressure applied with the thumb to a stopcock on the neck of the cylinder. Under the influence of the heat of the hand the liquid escapes in a fine jet which impinges on the patient’s skin. Freezing takes place in a few seconds, the frozen patch becoming hard and white. The freezing can be hastened by blowing on the skin.