232 Distribution of Hookworms 
suggest Malayan immigration to Polynesia, and these similarities may other¬ 
wise be explained. 
FURTHER OBSERVATIONS AND CONCLUSIONS. 
The hookworms harboured by a people depend on geographical, racial and 
climatic conditions and circumstances. 
A people can only harbour the worm species which have been existing as 
embryos in the soil of their immediate environment. 
The hookworms harboured by a person may disclose the influences to 
which he has been subjected in another environment. 
The relative number and species of hookworms will sometimes furnish 
indications as to the ethnic origin of a people about whose history there is 
no record. 
There has been a migration of rather large numbers of Asiatic people into 
parts of Indonesia. 
These people came from north of 20° N. latitude, probably India or 
Burmah, and colonized in fairly large numbers in mid and East Java, Bali, 
Timor, Lombok and Madura as is evidenced by the hookworm species formula 
of the people now resident there. Other parts of Indonesia may have been 
visited as no doubt they were, but not by people in sufficiently large numbers 
to affect appreciably the normal formula of Indonesian people. 
This Asiatic emigration did not extend to Polynesia, Fiji and Tonga for 
there are no helminthological evidences of it. 
Whatever migration to the South Seas occurred, if any, it must have 
taken place by people from south of 20° N. latitude, that is, from Madras, 
or Malay Peninsula, Sumatra or other parts of Indonesia or previous to the 
Asiatic colonization of Java and Bali. That is to say by a people with an 
ancylostome index amounting to nil. 
The presence of pure cultures or of relatively pure cultures of Necator in 
natives of Asia or Africa indicates that their hosts belong in the south rather 
than to the north, for the primitive distribution of Agchylostoma duodenale 
seems to have been limited to regions north of 20° N. latitude, while N. ameri- 
canus was distributed south of this line. 
A. duodenale may have been conveyed to or from the Orient along the old 
trade routes. But there are no evidences that Necator was introduced into 
Southern Europe from the east or into Egypt from South Africa for Necator 
is not found in Southern Europe or in Egypt. At any rate this species does 
not seem to be distributed to the latter places. 
Careful surveys are necessary here as elsewhere, for it must be remembered 
that N . americanus was for years overlooked in India by British, Dutch and 
French doctors, although the species exists there in enormous numbers. 
Practically every East Indian over 14 years of age living north of Calcutta 
being infected with both species. 
If certain tribes in America are found to be infected with A. duodenale as 
