The treatment consists in destroying the original papule by the actual cautery, acid nitrate of mercury, or pure carbolic acid.  The ulcers should be scraped with the sharp spoon, and cauterised.

CHIGOE.—­Chigoe or jigger results from the introduction of the eggs of the sand-flea (Pulex penetrans) into the tissues.  It occurs in tropical Africa, South America, and the West Indies.  The impregnated female flea remains attached to the part till the eggs mature, when by their irritation they cause localised inflammation with pustules or vesicles on the surface.  Children are most commonly attacked, particularly about the toe-nails and on the scrotum.  The treatment consists in picking out the insect with a blunt needle, special care being taken not to break it up.  The puncture is then cauterised.  The application of essential oils to the feet acts as a preventive.

POISONING BY INSECTS.—­The bites of certain insects, such as mosquitoes, midges, different varieties of flies, wasps, and spiders, may be followed by serious complications.  The effects are mainly due to the injection of an irritant acid secretion, the exact nature of which has not been ascertained.

The local lesion is a puncture, surrounded by a zone of hyperaemia, wheals, or vesicles, and is associated with burning sensations and itching which usually pass off in a few hours, but may recur at intervals, especially when the patient is warm in bed.  Scratching also reproduces the local signs and symptoms.  Where the connective tissue is loose—­for example, in the eyelid or scrotum—­there is often considerable swelling; and in the mouth and fauces this may lead to oedema of the glottis, which may prove fatal.

The treatment consists in the local application of dilute alkalies such as ammonia water, solutions of carbonate or bicarbonate of soda, or sal-volatile.  Weak carbolic lotions, or lead and opium lotion, are useful in allaying the local irritation.  One of the best means of neutralising the poison is to apply to the sting a drop of a mixture containing equal parts of pure carbolic acid and liquor ammoniae.

Free stimulation is called for when severe constitutional symptoms are present.

SNAKE-BITES.—­We are here only concerned with the injuries inflicted by the venomous varieties of snakes, the most important of which are the hooded snakes of India, the rattle-snakes of America, the horned snakes of Africa, the viper of Europe, and the adder of the United Kingdom.

While the virulence of these creatures varies widely, they are all capable of producing in a greater or less degree symptoms of acute poisoning in man and other animals.  By means of two recurved fangs attached to the upper jaw, and connected by a duct with poison-secreting glands, they introduce into their prey a thick, transparent, yellowish fluid, of acid reaction, probably of the nature of an albumose, and known as the venom.