69 
in 11.11 per cent of 36 children examined in the District of Columbia 
in 1895. 
The various reports of special outbreaks of uncinariasis among 
miners, brick makers, etc., do not as a rule furnish good statistical 
material. In the Westphalian coal mines of Germany official sta- 
tistics show (Bo}mott and Haldane, 1904, 105-106) that of 188,730 
miners employed in the district 17,101 (9.10 per cent) were infected 
with Agchylostoma duodenale at the beginning of the campaign 
against the disease; 63,000 men who worked in collieries which were 
declared infected with the parasite showed 12,157 infections, or 19.3 
per cent; under the energetic measures initiated the rate of infection 
in the infected collieries rapidly fell to 7.60 per cent. These figures 
are not included in the statistical summaries given below. 
There are a number of other places in which the population is 
known to be more or less generally infested with certain parasitic 
worms of the intestine, but for which we have no definite statistics. 
The most striking difference which appears, if we make a general 
comparison between our own results and those quoted, is the lower rate 
of infection among our cases. In the total number of infections, and 
almost always in the number of infections with each parasite as well, 
our percentages are lower than those given by any other investigators. 
On the other hand, our results differ from all but a few other 
researches in giving figures for Hymenolepis nana , Strongyloides ster- 
coralis, and for the hookworm. 
The whipworm ( Trichuris trichiura ) forms a larger proportion of 
the infections in our findings than in those of other authors. 
With regard to the relation between sex and the prevalence of 
intestinal worms found in the results of other investigations, we have 
summarized below the available statistics for each species of parasite 
in males and in females. This summary includes all cases examined 
by each author quoted in Table 3, so far as figures were given for the 
two sexes separately, except the Porto Ricans examined by Ashford, 
King, and Gutierrez; these Porto Rican statistics gave the proportion 
of infected males and females which appeared at the clinics of the 
commission, but not necessarily the relative frequency of infection 
in males and in females in the general population (see p. 30). 
