THE PROGRESS OF SCIENCE 



205 



Per cent, op increase in total Population by States, 1900-1910. 



lated states, followed in order by New 

 Jersey, Connecticut, New York, Penn- 

 sylvania, Maryland, Ohio, Delaware and 

 Illinois. The least density of popula- 

 tion is in the mountain states, Nevada 

 with less than one inhabitant to the 

 square mile ranking the lowest, fol- 

 lowed by Wyoming and Arizona. The 

 largest percentages of increase are 

 shown by the mountain and Pacific 

 states, Washington leading with an in- 

 crease of 120 per cent., followed by 

 Oklahoma and Idaho. As has already 

 been widely noted, Iowa shows an ac- 

 tual decrease in population. The states 

 of Missouri and Indiana show very 

 moderate increases; the rural New 

 England states also show small in- 

 creases of from four to seven per cent. 

 The increase in New- York is 25 per 

 cent, and in Pennsylvania 22 per cent. 



The urban population, which includes j 

 those residing in cities of 2,500 inhab- 

 itants or more, has increased 35 per j 

 cent., and the rural population 11 per 

 cent., seven tenths of the sixteen mil- 

 lion increase being in the cities. The 

 urban population is now 46 per cent.- of 

 the total population, whereas in 1880 

 it was 29 per cent. The three cities — 

 New York, Chicago and Philadelphia — 

 having a population of more than one 



million, show thirty-two per cent, in- 

 crease, while five cities, having a popu- 

 lation of 500,000 to one million, show 

 an increase of only 20 per cent. The 

 cities — 90 in number — having a popula- 

 tion of 50,000 to 250,000 show the 

 largest percentage of increase, namely,. 

 41 per cent. In New England and the 

 Atlantic states about three quarters of 

 the people live in the cities. 



THE ERADICATION OF HOOK- 

 TV OEM DISEASE 



The second annual report of the 

 Rockefeller Sanitary Commission tells 

 the story of a dramatic achievement of 

 modern sanitary medicine. It will be 

 remembered that the existence of hook- 

 worm disease in the south was not sus- 

 pected until recently. It has now been 

 found to be extremely prevalent. In 

 the infection survey of the commission 

 87 counties were covered, 37,267 chil- 

 dren examined, and the percentage of 

 infection by counties was found to 

 range from 2.5 to 90.2 per cent. In 

 some schools practically every child was 

 infected, and a large percentage of all 

 children were unable to attend school. 

 The disease is particularly disastrous 

 in its consequences, for though not or- 

 dinarily fatal, like malaria it prevents 



