It is an interesting and really instructive thing to pass in review the gradual process by which the cleanliness of the population of Western Europe has advanced, and to observe that, consciously or unconsciously, the end pursued has been, step by step, the removal from man's body outside (and inside), from his clothing, from the water he drinks, from the food he eats, from the air he breathes, and from the surfaces with which he necessarily comes into contact, of injurious parasites and hurtful living things which lurk in dirt and rubbish. At first the larger and more obvious hurtful creatures--snakes, rats, mice, scorpions, blow-flies--were eliminated by some elementary attempts at removal of rubbish and kitchen middens. Then ticks (which African savages still do not trouble to remove from their bodies) and later fleas and bugs became unpopular; lice were long regarded as inevitable, and even beneficial, and by some populations and by part of the most civilised at the present day, are still, not merely tolerated, but favoured. In a country school in France a child who was found to be afflicted in this way was the daughter of the local medical practitioner. She remarked, "Oh! Ce n'est rien; papa dit que c'est la sante des enfants"! Parasitic worms of various kinds, though they often cause disease and death, are accepted and tolerated even by the most refined and luxurious, who risk infection rather than submit to the precaution of abstention from raw vegetables and fruits, or to the expenditure of trouble in cleansing those nests of infective germs. It is only within the last thirty or forty years that such cleanliness of body and of clothing and of house-fittings as will banish parasitic insects has become at all general. The common house-fly is still tolerated, although it is a notorious carrier of dirt and disease, and is bred by dirt and dirt only, its eggs being hatched in old stable manure. The diminution of late years of house-flies in London houses is simply and solely due to legislation compelling the removal of horse manure from the "mews" so frequent at the back of London streets. Egyptian natives still allow flies to gather on their eyelids without protest.