The _mass_ of poverty and wretchedness is, of course, far greater in the English capital. There are classes with inherited pauperism and crime more deeply stamped in them, in London or Glasgow, than we ever behold in New York; but certain small districts can be found in our metropolis with the unhappy fame of containing more human beings packed to the square yard, and stained with more acts of blood and riot, within a given period, than is true of any other equal space of earth in the civilized world. There are houses, well known to sanitary boards and the police, where Fever has taken a perennial lease, and will obey no legal summons to quit; where Cholera--if a single germ-seed of it float anywhere in American atmosphere--at once ripens a black harvest; where Murder has stained every floor of its gloomy stories, and Vice skulks or riots from one year's end to the other. Such houses are never reformed. The only hope for them is in the march of street improvements, which will utterly sweep them away. It is often urged that the breaking-up of these "dens" and "fever-nests" only scatters the pestilence and moral disease, but does not put an end to them. The objection is more apparent than real. The abolishing of one of these centres of crime and poverty is somewhat like withdrawing the virus from one diseased limb and diffusing it through an otherwise healthy body. It seems to lose its intensity. The diffusion weakens. Above all, it is less likely to become hereditary. One of the remarkable and hopeful things about New York, to a close observer of its "dangerous classes," is, as I shall show in a future chapter, that they do not tend to become fixed and inherited, as in European cities.