"I think the sanitarian can now show that any population coming into the tropics can protect itself against these two diseases [malaria and yellow fever] by measures that are both simple and inexpensive; that with these two diseases eliminated life in the tropics for the Anglo-Saxon will be more healthful than in the temperate zones; that gradually, within the next two or three centuries, tropical countries, which offer a much greater return for man's labour than do the temperate zones, will be settled up by the white races, and that again the centres of wealth, civilisation and population will be in the tropics, as they were in the dawn of man's history, rather than in the temperate zone, as at present." [31] "Sanitation in the Canal Zone." In this connection I may perhaps be permitted to refer to an interesting suggestion made in the course of conversation by Colonel Gorgas, although I omitted to inquire if it had been published. This suggestion was that the records of the movements of great armies under the rulers of ancient Mesopotamia and Egypt indicate that malaria did not then exist in the nearer East, and that malaria, like yellow fever, was once a local disease. [Illustration: NEAR THE SITE OF MILAFLORES LOCKS.] [Illustration: LOOKING NORTH TO CULEBRA DIVIDE FROM ANCON HILL.] From what I have seen as tourist and traveller (not as resident) in the West Indies and in the Orient, I have arrived at the following tentative conclusions, viz.:-- That the debilitating effect which the tropics have been observed to exercise upon those who come from temperate regions has been due mainly to the presence of certain diseases which can be done away with. That the rapid deterioration of the white stock which is usually noticed in the tropics, especially near the equator, is mainly due to the same cause. But that Anglo-Saxons cannot perform nearly the same amount of hard bodily labour in a constantly hot climate as they can in the temperate zone, and Anglo-Saxon immigrants never will be able to do so. In this I think the Mediterranean races--at all events the Spaniards and Italians--are our superiors. Whether the descendants of Anglo-Saxon stock who have settled in a tropical country purified from tropical diseases will be able to support continued hard bodily labour better than their immigrant ancestors is a matter about which we have at present no direct evidence. It may possibly be worth noting, however, that some years ago, when wintering in Manitoba, I found that some of the farmer immigrants from England felt the cold more as the years went by, but that their children born in the country were unaffected by it.