"The evil of overcrowding is aggravated by causes which derive their origin from the effects of that condition itself. A lowered standard of health, always the accompaniment of close building, is a factor in the further increase of pressure in an already congested district. An unsatisfied demand in the labour market for physical strength is a necessary outcome of that quality in the district affected. Muscle and bone in such a locality is at a premium, and that which cannot be supplied in its full development from within must be sought and obtained from without." "Here, then, is a vicious circle of concurrent cause and effect. Overcrowding is the cause of physical weakness: physical weakness results in an unsatisfied demand in the labour market: the unsatisfied demand is the cause of an influx from without: again that influx results in overcrowding." Once, then, that the influx of the physically strong began to diminish--the element which had contributed most to the maintenance of the physical vigour and health of the population of London--it was evident that deterioration would ensue, and the only means of counteracting that result was to improve to the utmost possible the sanitary conditions in which the people lived. The census of 1881 is remarkable as being the last to show an increase of country-born immigrants into London. That tide was soon to begin to ebb. The immigrants, however, were far from being all of a desirable character. The Medical Officer of Health for Camberwell pointed this out:-- "A considerable percentage of our population is composed of persons whose natural tendency is to grovel--beggars, thieves, prostitutes, drunkards, persons of feeble intelligence, persons of lazy and improvident habits, and persons who (like too many of the poor) marry or cohabit prematurely and procreate large families for which they are totally unable to provide; and such persons gravitate from all quarters to large towns and there accumulate.... A large town like London will always attract undesirable residents." With the increasing population the number of houses in the metropolis increased also. From 418,802 inhabited houses in 1871 the number had gone up to 488,116 in 1881, and the same tale was told as to the crowding of houses on the land as in previous years. The Medical Officer of Health for Bethnal Green (1880) stated that in his parish most of the available ground was already fully built over. The Great Eastern Railway Company, the School Board for London, and the Metropolitan Board of Works, were largely demolishing small house property. "If this sort of thing goes on much longer," he wrote, "it looks very much as if London in a few years would become a huge agglomeration of Board Schools, intersected by railways and new streets." The correct record of the population enabled once more an accurate death-rate to be calculated. The death-rate, which had been 24·6 per 1,000 in 1871, had fallen to 21·3 in 1881.