30 
position of the sex toward the parasite as it is a question of the rela- 
tive intimacy existing between the average daily life of the sex and the 
more concentrated infectious material. 
Thus, also, the difference in frequency of parasitism observed in the 
Connecticut and the St. Elizabeth women may be explained, at least in 
part, by the fact that the Connecticut female patients appear to have 
been recruited more from rural life, while the St. Elizabeth female 
patients appear to have been recruited almost entirely from city life. 
In connection with hookworm disease in Porto Rico, Ashford, King, 
and Gutierrez (1904, 54) state that of 5,490 hookworm patients, 3,259 
were males and 2,231, or 40.6 per cent, were females. This difference 
they interpret as largely due to chances offered for infection, “ males 
naturally being more exposed from the nature of their occupation.' 1 
This conclusion is not quite so evident to us. In connection with 
this interesting question they bring out the fact (p. 49) that the 
laborers on coffee estates are doubly exposed to infection, namely, 
in that the environment of their dwellings is loaded with hookworm 
larvse and in that a similar condition exists at their place of work. 
It may be pointed out that the infection around the houses would as a 
rule naturally be the severer: now it is, in general, the women and 
children who are subjected more to this concentrated infection than are 
the males; hence, other things being equal, it is among the females 
that the heavier infection would be expected. The question natur- 
ally arises, therefore, whether there is not some explanation other 
than occupation which would account for the higher number of male 
patients reported for Porto Rico. One such possibility occurs to us, 
namely, as stated by our colleagues, their patients came to the clinics, 
and many of them were obliged to walk miles in order to reach the 
place of treatment; their sex statistics therefore represent the num- 
ber of males and females who visited the clinic and not the proportion 
of infected to noninfected males and females in the island, and the 
question would naturally arise whether males would not be more likely 
to visit the clinic than would the females, and whether the statistics 
would not have been reversed had they been based upon observations 
made at the homes instead of at the clinics. This possible interpreta- 
tion is strengthened rather than weakened by the statement that “ the 
degree of anaemia is less in females than in males, obeying to a certain 
extent, at least, the number of parasites with which each sex is 
infected," a statement which naturally gives rise to the thought that 
the severer female cases possibly failed to visit the clinic. A final 
point is that the sex statistics as reported are actual numbers and not 
the percentages of the infected to the uninfected; hence they do not 
represent the relative tendency of the two sexes to infection. 
Age. — In interpreting age as a factor in parasitism the conditions 
would appear theoretically even more complicated. Several authors 
