INFANT MORTALITY AND THE ENVIRONMENT. 227 



laundry purposes, and the stinking vault still maintains its posi- 

 tion in the back yard. Observe this fact also : a considerable ma- 

 jority of the population of New Haven resides upon the sewered 

 streets, and yet only nine out of forty -three deaths from a disease 

 which is chiefly caused by foul air occur among the majority ; 

 while thirty-four of the forty-three are among the minority, who 

 reside in dwellings surrounded by the fragrant companionship of 

 time-honored filth-pits. Any person can draw intelligent infer- 

 ence from the above plain facts." 



The remaining important factor in the production of infantile 

 diarrhoea is overcrowding. This, indeed, is but the occasion of 

 one of the most dangerous forms of filth, in the shape of air de- 

 prived of its vitalizing qualities, and charged with impurities 

 derived from the breath and bodies of men and animals, which 

 is sometimes known as " crowd-poison." " It is this air," says Dr. 

 Richardson, " in our overcrowded towns and cities, where there 

 is no vegetation to revivify it, which we distinguish as something 

 so different from the fresh country air that streams over meadow 

 and forest. It is the breathing of this air that makes the child of 

 the town so pale and lax and feeble, as compared with the child 

 of the country. It is this air that renders the atmosphere of the 

 crowded hospital so deficient in sustaining power. It is this air 

 that gives to many of our public institutions, in which large 

 masses of our poorer, ill-clad, uncleansed masses are herded to- 

 gether, that ' poor-smell,^ as it is called, which is so depressing 

 both to the senses and to the animal power." 



Cholera infantum is well known to be almost exclusively a dis- 

 ease of cities, and absolutely so in its epidemic form. The city of 

 Manchester, N. H,, contains only about one tenth of the population 

 of the State, yet in 1883 it furnished nearly one half of the whole 

 number of deaths from this disease ; while in 1885, the three cities 

 of Dover, Portsmouth, and Manchester, together containing less 

 than one sixth of the whole population, reported considerably 

 more than one half of the entire mortality from cholera infantum. 

 The State of Massachusetts contains eighteen cities and towns of 

 more than fifteen thousand inhabitants, while Vermont has none. 

 The mortality from cholera infantum in 1883 was 3'49 per 10,000 

 in Vermont, and 9*53 per 10,000 in Massachusetts. 



According to Dr. Farr, the mortality of districts increases with 

 the density of their population ; not, however, in the direct pro- 

 portion of their densities, but as the sixth root of their densities. 

 But while the total mortality increases in this proportion, the 

 mortality imder five increases in a much greater ratio. Thus, 

 with a density of 166 to a square mile, the death-rate at all ages 

 is 16'94 per 1,000, while of those under five it is 37-8 per 1,000. 

 This ratio increases gradually and with considerable regularity 



